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                                                                     Exhibit 4.1

                                                                  EXECUTION COPY

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                   2.875% Convertible Subordinated Debentures

                            Dated as of June 21, 2004

                                   ----------

                                     Between

                     Charles River Associates Incorporated,

                                   as Issuer,

                                       and

                         U.S. Bank National Association,

                                   as Trustee

                                   ----------

                                    INDENTURE

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                                TABLE OF CONTENTS

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                                                    ARTICLE 1
                                                   DEFINITIONS

      SECTION 1.01. Definitions................................................................................1

                                                    ARTICLE 2
                      ISSUE, DESCRIPTION, EXECUTION, REGISTRATION AND EXCHANGE OF DEBENTURES

      SECTION 2.01. Amount of Debentures......................................................................14
      SECTION 2.02. Form and Dating...........................................................................14
      SECTION 2.03. Execution and Authentication..............................................................15
      SECTION 2.04. Debenture Registrar and Paying Agent......................................................15
      SECTION 2.05. Paying Agent to Hold Money in Trust.......................................................16
      SECTION 2.06. Holder Lists..............................................................................16
      SECTION 2.07. Transfer and Exchange.....................................................................16
      SECTION 2.08. Replacement Debentures....................................................................17
      SECTION 2.09. Outstanding Debentures....................................................................18
      SECTION 2.10. Temporary Debentures......................................................................18
      SECTION 2.11. Cancellation..............................................................................18
      SECTION 2.12. Defaulted Interest........................................................................19
      SECTION 2.13. CUSIP and ISIN Numbers....................................................................19

                                                    ARTICLE 3
                                     REDEMPTION AND REPURCHASE OF DEBENTURES

      SECTION 3.01. Redemption................................................................................19
      SECTION 3.02. Notice of Redemption; Selection of Debentures.............................................19
      SECTION 3.03. Payment of Debentures Called for Redemption by the Company................................21
      SECTION 3.04. Conversion Arrangement on Call for Redemption.............................................22
      SECTION 3.05. Repurchase of Debentures by the Company at Option of Holders upon a Fundamental Change....22
      SECTION 3.06. Repurchase of Debentures by the Company at Option of Holders on Specified Dates...........26
      SECTION 3.07. Reserved..................................................................................28
      SECTION 3.08. Conditions and Procedures for Repurchase at Option of Holders.............................28

                                                    ARTICLE 4
                                       PARTICULAR COVENANTS OF THE COMPANY

      SECTION 4.01. Payment of Principal and Interest.........................................................31
      SECTION 4.02. Maintenance of Office or Agency...........................................................31
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      SECTION 4.03. Appointments to Fill Vacancies in Trustee's Office........................................32
      SECTION 4.04. Provisions as to Paying Agent.............................................................32
      SECTION 4.05. Existence.................................................................................33
      SECTION 4.06. Rule 144A Information Requirement.........................................................33
      SECTION 4.07. Stay, Extension and Usury Laws............................................................33
      SECTION 4.08. Compliance Certificate....................................................................34
      SECTION 4.09. Additional Interest Notice................................................................34
      SECTION 4.10. Contingent Debt Tax Treatment.............................................................34

                                                    ARTICLE 5
                        DEBENTUREHOLDERS' LISTS AND REPORTS BY THE COMPANY AND THE TRUSTEE

      SECTION 5.01. Debentureholders' Lists...................................................................35
      SECTION 5.02. Preservation and Disclosure of Lists......................................................35
      SECTION 5.03. Reports by Trustee........................................................................35
      SECTION 5.04. Reports by the Company....................................................................36

                                                    ARTICLE 6
                       REMEDIES OF THE TRUSTEE AND DEBENTUREHOLDERS ON AN EVENT OF DEFAULT

      SECTION 6.01. Events of Default.........................................................................36
      SECTION 6.02. Payments of Debentures on Default; Suit Therefor..........................................38
      SECTION 6.03. Application of Monies Collected by Trustee................................................40
      SECTION 6.04. Proceedings by Debentureholder............................................................41
      SECTION 6.05. Proceedings by Trustee....................................................................41
      SECTION 6.06. Remedies Cumulative and Continuing........................................................42
      SECTION 6.07. Direction of Proceedings and Waiver of Defaults by Majority of Debentureholders...........42
      SECTION 6.08. Notice of Defaults........................................................................42
      SECTION 6.09. Undertaking to Pay Costs..................................................................43

                                                    ARTICLE 7
                                                   THE TRUSTEE

      SECTION 7.01. Duties of Trustee.........................................................................43
      SECTION 7.02. Rights of Trustee.........................................................................44
      SECTION 7.03. Individual Rights of Trustee..............................................................45
      SECTION 7.04. Trustee's Disclaimer......................................................................45
      SECTION 7.05. Reports by Trustee to Holders.............................................................46
      SECTION 7.06. Compensation and Indemnity................................................................46
      SECTION 7.07. Replacement of Trustee....................................................................47
      SECTION 7.08. Successor Trustee by Merger...............................................................48
      SECTION 7.09. Eligibility; Disqualification.............................................................48
      SECTION 7.10. Preferential Collection of Claims Against Company.........................................48
</Table>

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                                                    ARTICLE 8
                                               THE DEBENTUREHOLDERS

      SECTION 8.01. Action by Debentureholders................................................................48
      SECTION 8.02. Proof of Execution by Debentureholders....................................................49
      SECTION 8.03. Who Are Deemed Absolute Owners............................................................49
      SECTION 8.04. Company owned Debentures Disregarded......................................................49
      SECTION 8.05. Revocation of Consents, Future Holders Bound..............................................49

                                                    ARTICLE 9
                                           MEETINGS OF DEBENTUREHOLDERS

      SECTION 9.01. Purpose of Meetings.......................................................................50
      SECTION 9.02. Call of Meetings by Trustee...............................................................50
      SECTION 9.03. Call of Meetings by Company or Debentureholders...........................................51
      SECTION 9.04. Qualifications for Voting.................................................................51
      SECTION 9.05. Regulations...............................................................................51
      SECTION 9.06. Voting....................................................................................52
      SECTION 9.07. No Delay of Rights by Meeting.............................................................52

                                                    ARTICLE 10
                                             SUPPLEMENTAL INDENTURES

      SECTION 10.01. Supplemental Indentures Without Consent of Debentureholders..............................53
      SECTION 10.02. Supplemental Indenture with Consent of Debentureholders..................................54
      SECTION 10.03. Effect of Supplemental Indenture.........................................................56
      SECTION 10.04. Notation on Debentures...................................................................56
      SECTION 10.05. Trustee to Sign Supplemental Indentures..................................................56

                                                    ARTICLE 11
                                CONSOLIDATION, MERGER, SALE, CONVEYANCE AND LEASE

      SECTION 11.01. Company May Consolidate on Certain Terms.................................................56
      SECTION 11.02. Successor to Be Substituted..............................................................57
      SECTION 11.03. Opinion of Counsel to Be Given Trustee...................................................58

                                                    ARTICLE 12
                                     SATISFACTION AND DISCHARGE OF INDENTURE

      SECTION 12.01. Discharge of Indenture...................................................................58
      SECTION 12.02. Application of Trust Money...............................................................58
      SECTION 12.03. Paying Agent to Repay Monies Held........................................................59
      SECTION 12.04. Return of Unclaimed Monies...............................................................59

                                                    ARTICLE 13
                         IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS

      SECTION 13.01. Indenture and Debentures Solely Corporate Obligations....................................59
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                                                    ARTICLE 14
                                               CONTINGENT INTEREST

      SECTION 14.01. Contingent Interest......................................................................59
      SECTION 14.02. Payment of Contingent Interest...........................................................60
      SECTION 14.03. Contingent Interest Notification.........................................................60

                                                    ARTICLE 15
                                             CONVERSION OF DEBENTURES

      SECTION 15.01. Right to Convert.........................................................................60
      SECTION 15.02. Exercise of Conversion Privilege; Issuance of Common Stock on Conversion; No
                      Adjustment for Interest or Dividends; Settlement of Cash or Common Stock
                      upon Conversion.........................................................................64
      SECTION 15.03. Cash Payments in Lieu of Fractional Shares...............................................68
      SECTION 15.04. Conversion Rate..........................................................................68
      SECTION 15.05. Adjustment of Conversion Rate............................................................68
      SECTION 15.06. Effect of Reclassification, Consolidation, Merger or Sale................................75
      SECTION 15.07. Taxes on Shares Issued...................................................................76
      SECTION 15.08. Reservation of Shares, Shares to Be Fully Paid; Compliance with Governmental
                      Requirements; Listing of Common Stock...................................................76
      SECTION 15.09. Responsibility of Trustee................................................................77
      SECTION 15.10. Notice to Holders Prior to Certain Actions...............................................78
      SECTION 15.11. Shareholder Rights Plan..................................................................79

                                                 ARTICLE 16
                                          MISCELLANEOUS PROVISIONS

      SECTION 16.01. Intentionally Omitted....................................................................79
      SECTION 16.02. Provisions Binding on Successors.........................................................79
      SECTION 16.03. Official Acts by Successor Corporation...................................................79
      SECTION 16.04. Addresses for Notices, Etc...............................................................79
      SECTION 16.05. Governing Law............................................................................80
      SECTION 16.06. Evidence of Compliance with Conditions Precedent, Certificates to Trustee................80
      SECTION 16.07. Legal Holidays...........................................................................81
      SECTION 16.08. Company Responsible for Making Calculations..............................................81
      SECTION 16.09. Trust Indenture Act......................................................................81
      SECTION 16.10. No Security Interest Created.............................................................81
      SECTION 16.11. Benefits of Indenture....................................................................81
      SECTION 16.12. Table of Contents, Headings, Etc.........................................................82
      SECTION 16.13. Authenticating Agent.....................................................................82
      SECTION 16.14. Execution in Counterparts................................................................83
      SECTION 16.15. Severability.............................................................................83

                                                 ARTICLE 17
                                               SUBORDINATION
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      SECTION 17.01. Agreement to Subordinate.................................................................83
      SECTION 17.02. Liquidation, Dissolution, Bankruptcy.....................................................83
      SECTION 17.03. Default on Senior Debt and/or Designated Senior Debt.....................................83
      SECTION 17.04. Acceleration of Debentures...............................................................84
      SECTION 17.05. When Distribution Must Be Paid Over......................................................84
      SECTION 17.06. Notice by Company........................................................................85
      SECTION 17.07. Subrogation..............................................................................85
      SECTION 17.08. Relative Rights..........................................................................85
      SECTION 17.09. Subordination May Not Be Impaired by Company.............................................86
      SECTION 17.10. Distribution or Notice to Representative.................................................86
      SECTION 17.11. Rights of Trustee and Paying Agent.......................................................86
      SECTION 17.12. Authorization to Effect Subordination....................................................87
      SECTION 17.13. Article Applicable to Paying Agents......................................................87
      SECTION 17.14. Senior Debt Entitled to Rely.............................................................87
      SECTION 17.15. Permitted Payments.......................................................................87
      SECTION 17.16. No Waiver of Subordination Provisions....................................................87

Appendix A   Provisions Relating to Debentures...............................................................A-1
Exhibit A    Form of Debenture...............................................................................E-1
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                              CROSS-REFERENCE TABLE

<Table>
<Caption>
Trust Indenture Act Section                                                         Indenture Section
---------------------------                                                         -----------------
<S>                                                                                 <C>
310(a)(1).........................................................................  7.09
   (a)(2).........................................................................  7.09
   (a)(3).........................................................................  N.A.
   (a)(4).........................................................................  N.A.
   (b)............................................................................  7.07; 7.09
   (c)............................................................................  N.A.
311(a)............................................................................  7.10
   (b)............................................................................  7.10
   (c)............................................................................  N.A.
312(a)............................................................................  2.06; 5.01
   (b)............................................................................  5.02(b)
   (c)............................................................................  5.02(c)
313(a)............................................................................  7.05; 5.03(a)
   (b)(1).........................................................................  N.A.
   (b)(2).........................................................................  7.05
   (c)............................................................................  16.04
   (d)............................................................................  7.05; 5.03(b)
314(a)............................................................................  5.04; 16.04
   (b)............................................................................  N.A.
   (c)(1).........................................................................  16.06
   (c)(2).........................................................................  16.06
   (c)(3).........................................................................  N.A.
   (d)............................................................................  N.A.
   (e)............................................................................  16.06
   (f)............................................................................  N.A.
315(a)............................................................................  7.01
   (b)............................................................................  6.08; 16.04
   (c)............................................................................  7.01; 7.02
   (d)............................................................................  7.01
   (e)............................................................................  6.09
316(a)(last sentence).............................................................  8.04
   (a)(1)(A)......................................................................  6.04; 6.07
   (a)(1)(B)......................................................................  6.07
   (a)(2).........................................................................  N.A.
   (b)............................................................................  6.04
317(a)(1).........................................................................  6.05
   (a)(2).........................................................................  6.05 (implied)
   (b)............................................................................  2.05
318(a)............................................................................  16.09
</Table>

N.A. means Not Applicable.
Note: This Cross-Reference Table shall not, for any purpose, be deemed to be
part of this Indenture.

                                       vi
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                                    INDENTURE

          INDENTURE dated as of June 21, 2004, among CHARLES RIVER ASSOCIATES
INCORPORATED, a Massachusetts corporation (hereinafter called the "COMPANY"),
having its principal office at 200 Clarendon Street, T-33, Boston, Massachusetts
02116, and U.S. BANK NATIONAL ASSOCIATION, as trustee hereunder (hereinafter
called the "TRUSTEE").

                                   WITNESSETH:

          WHEREAS, for its lawful corporate purposes, the Company has duly
authorized the issue of its 2.875% Convertible Subordinated Debentures due 2034
(hereinafter called the "DEBENTURES"), in an aggregate principal amount up to
$75,000,000 (or up to $90,000,000 if the Initial Purchasers' (as hereinafter
defined) option to purchase additional Debentures set forth in the Purchase
Agreement (as hereinafter defined) is exercised in full), and, to provide the
terms and conditions upon which the Debentures are to be authenticated, issued
and delivered, the Company has duly authorized the execution and delivery of
this Indenture.

          WHEREAS, the Debentures, the certificate of authentication to be borne
by the Debentures, a form of assignment, a form of fundamental change repurchase
election, a form of Company repurchase election and a form of conversion notice
to be borne by the Debentures are to be substantially in the forms hereinafter
provided for.

          WHEREAS, all acts and things necessary to make the Debentures, when
executed by the Company, as applicable, and authenticated and delivered by the
Trustee or a duly authorized authenticating agent, as in this Indenture
provided, the valid, binding and legal obligations of the Company, as
applicable, and to constitute this Indenture a valid agreement according to its
terms, have been done and performed, and the execution of this Indenture and the
issue hereunder of the Debentures have in all respects been duly authorized; and
in addition, all things necessary to duly authorize the issuance of the Common
Stock (as hereinafter defined) of the Company initially issuable upon the
conversion of the Debentures, and to duly reserve for issuance the number of
shares of Common Stock initially issuable upon such conversion, have been done.

          NOW, THEREFORE, THIS INDENTURE WITNESSETH:

          That in order to declare the terms and conditions upon which the
Debentures are, and are to be, authenticated, issued and delivered, and in
consideration of the premises and of the purchase and acceptance of the
Debentures by the holders thereof, the Company covenants and agrees with the
Trustee for the equal and proportionate benefit of the respective holders from
time to time of the Debentures (except as otherwise provided below), as follows:

                                    ARTICLE 1
                                   DEFINITIONS

          SECTION 1.01.  DEFINITIONS. The terms defined in this Section 1.01
(except as herein otherwise expressly provided or unless the context otherwise
requires) for all purposes of this Indenture and of any indenture supplemental
hereto shall have the respective meanings

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specified in this Section 1.01. All other terms used in this Indenture that are
defined in the Trust Indenture Act or which are by reference therein defined in
the Securities Act (except as herein otherwise expressly provided or unless the
context otherwise requires) shall have the meanings assigned to such terms in
the Trust Indenture Act and in the Securities Act as in force at the date of the
execution of this Indenture. The words "herein", "hereof", "hereunder" and words
of similar import refer to this Indenture as a whole and not to any particular
Article, Section or other Subdivision. The terms defined in this Article include
the plural as well as the singular.

          "ADDITIONAL INTEREST" has the meaning specified in the Registration
Rights Agreement.

          "ADDITIONAL INTEREST NOTICE" has the meaning specified in Section
4.09.

          "ADDITIONAL PREMIUM" has the meaning specified in Section 3.05(d).

          "ADJUSTMENT EVENT" has the meaning specified in Section 15.05(l).

          "AFFILIATE" of any specified Person means any other Person directly or
indirectly controlling or controlled by or under direct or indirect common
control with such specified Person. For the purposes of this definition,
"CONTROL", when used with respect to any specified Person, means the power to
direct or cause the direction of the management and policies of such Person,
directly or indirectly, whether through the ownership of voting securities, by
contract or otherwise, and the terms "CONTROLLING" and "CONTROLLED" have
meanings correlative to the foregoing.

          "APPLICABLE FIVE-DAY TRADING PERIOD" means, with respect to any
Interest Period as to which Contingent Interest may be payable, the five Trading
Days immediately preceding the first day of such Interest Period.

          "BANKRUPTCY LAW" means Title 11, United States Bankruptcy Code of
1978, as amended, or any similar United States federal or state law relating to
the bankruptcy, insolvency, receivership, winding-up, liquidation,
reorganization or relief of debtors or any amendment to, successor to or change
in any such law.

          "BID SOLICITATION AGENT" means such Person (other than any Affiliate
of the Company) as the Company may designate as Bid Solicitation Agent from time
to time, and shall initially mean the Trustee.

          "BOARD OF DIRECTORS" means, with respect to a Person, the Board of
Directors of such Person or any committee of such Board duly authorized to act
on behalf of such Board, or, if such Person is not a corporation, the equivalent
governing or managing body, authority or individual. Unless otherwise indicated,
references to the Board of Directors shall mean the Board of Directors of the
Company.

          "BOARD RESOLUTION" means a resolution duly adopted by the Board of
Directors of a Person, a copy of which, certified by the Secretary or an
Assistant Secretary of such Person or, if such Person is not a corporation, the
equivalent officer, to be in full force and effect on the date of such
certification, shall have been delivered to the Trustee. Unless otherwise
indicated,

                                        2
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references to a Board Resolution shall mean a Board Resolution of the Board of
Directors of the Company.

          "BUSINESS DAY" means any day, other than a Saturday or Sunday, that is
neither a legal holiday nor a day on which commercial banking institutions are
authorized or required by law, regulation or executive order to close in The
City of New York.

          "CAPITAL STOCK" of any Person means any and all shares (including
ordinary shares or American Depositary Shares), interests, participations or
other equivalents, however designated, of capital stock or other equity
participations, including partnership interests, whether general or limited, of
such Person (collectively an "equity interest") and any and all rights (other
than debt securities convertible or exchangeable into an equity interest),
warrants or options to acquire an equity interest in such Person.

          "CASH" has the meaning specified in Section 3.07(a).

          "CASH AMOUNT" has the meaning specified in Section 15.02(h)(iii).

          "CASH SETTLEMENT AVERAGING PERIOD" has the meaning specified in
Section 15.02(h)(ii)(B).

          "CASH SETTLEMENT NOTICE PERIOD" has the meaning specified in Section
15.02(g)(i).

          "CLOSING TRADING PRICE" with respect to calculating the Make-Whole
Premium on any date of determination, means the average of the secondary market
bid quotations per Debenture obtained by the Trustee for $2,000,000 aggregate
principal amount of the Debentures at approximately 3:30 p.m., New York City
time, on such determination date from three independent nationally recognized
securities dealers (none of which shall be the Company or an Affiliate thereof)
in The City of New York (or such other place that may be determined from time to
time by the Company) selected by the Company; PROVIDED, HOWEVER, if at least
three such bids cannot reasonably be obtained by the Trustee, but two such bids
are obtained, then the average of the two bids shall be used, and if only one
such bid can reasonably be obtained by the Trustee, that one bid shall be used.
If the Trustee cannot reasonably obtain at least one bid for $2,000,000
principal amount of Debentures from an independent nationally recognized
securities dealer, then the Closing Trading Price per $1,000 principal amount of
Debentures will be deemed to be the product of (x) the average of the closing
prices of the Common Stock for the five trading days immediately prior to the
public announcement of Fundamental Change and (y) the applicable Conversion
Rate.

          "COMMISSION" means the Securities and Exchange Commission, as from
time to time constituted under the Exchange Act, or, if at any time after the
execution of this Indenture such Commission is not existing and performing the
duties now assigned to it under the Trust Indenture Act, then the body
performing such duties at such time.

          "COMMON STOCK" means any stock of any class of the Company which has
no preference in respect of dividends or of amounts payable in the event of any
voluntary or involuntary liquidation, dissolution or winding up of the Company
and which is not subject to

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redemption by the Company. Subject to the provisions of Section 15.06, however,
shares issuable on conversion of Debentures shall include only shares of the
class designated as common stock of the Company at the date of this Indenture
(namely, the Common Stock, no par value) or shares of any class or classes
resulting from any reclassification or reclassifications thereof and which have
no preference in respect of dividends or of amounts payable in the event of any
voluntary or involuntary liquidation, dissolution or winding up of the Company
and which are not subject to redemption by the Company; PROVIDED that if at any
time there shall be more than one such resulting class, the shares of each such
class then so issuable on conversion shall be substantially in the proportion
which the total number of shares of such class resulting from all such
reclassifications bears to the total number of shares of all such classes
resulting from all such reclassifications.

          "COMPANY" means the corporation named as the "Company" in the first
paragraph of this Indenture, and, subject to the provisions of Article 11 and
Section 15.06, shall include its successors and assigns.

          "COMPANY REPURCHASE DATE" has the meaning specified in Section
3.06(a).

          "COMPANY REPURCHASE ELECTION" has the meaning specified in Section
3.06(c)(i).

          "COMPANY REPURCHASE NOTICE" has the meaning specified in Section
3.06(b).

          "COMPANY REPURCHASE PRICE" has the meaning specified in Section
3.06(a).

          "CONTINGENT DEBT REGULATIONS" has the meaning specified in Section
14.10.

          "CONTINGENT INTEREST" has the meaning specified in Section 14.01.

          "CONVERSION AGENT" means the Trustee or such other office or agency
designated by the Company where Debentures may be presented for conversion.

          "CONVERSION DATE" has the meaning specified in Section 15.02(c).

          "CONVERSION OBLIGATION" has the meaning specified in Section
15.02(g)(i).

          "CONVERSION PRICE" as of any day means $1,000 divided by the
Conversion Rate as of such date and rounded to the nearest cent. The Conversion
Price shall initially be $40.00 per share of Common Stock.

          "CONVERSION RATE" has the meaning specified in Section 15.04.

          "CONVERSION RETRACTION PERIOD" has the meaning specified in Section
15.02(g)(i).

          "CORPORATE TRUST OFFICE" or other similar term means (a) the
designated office of the Trustee at which at any particular time its corporate
trust business as it relates to this Indenture shall be administered, which
office is, at the date as of which this Indenture is dated,

                                        4
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located at One Federal Street, Third Floor, Boston, Massachusetts 02110, Attn:
Corporate Trust Services, or at any other address as the Trustee may designate
from time to time by notice to the holders and (b) with respect to Section
3.05(c), Section 3.06(c) or Section 15.02, the office of the Trustee located in
the Borough of Manhattan, which office is, at the date as of which this
Indenture is dated, located at 100 Wall Street, Suite 1600, New York, New York
10005.

          "CUSTODIAN" means U.S. Bank National Association, as custodian with
respect to the Debentures in global form, or any successor entity thereto.

          "DEBENTURE" OR "DEBENTURES" means any Debenture or Debentures, as the
case may be, authenticated and delivered under this Indenture, including any
Global Debenture.

          "DEBENTURE REGISTER" has the meaning specified in Section 2.04.

          "DEBENTURE REGISTRAR" has the meaning specified in Section 2.04.

          "DEBENTUREHOLDER" or "HOLDER" as applied to any Debenture, or other
similar terms (including the term "HOLDER OF RECORD" but excluding the terms
"BENEFICIAL HOLDER" and "BENEFICIAL OWNER" ), means any Person in whose name a
particular Debenture is registered at the time on the Debenture Registrar's
books.

          "DEFAULT" means any event that is, or after notice or passage of time,
or both, would be, an Event of Default.

          "DEFAULTED INTEREST" means any interest on any Debentures which is
payable, but is not punctually paid or duly provided for, on any June 15 or
December 15.

          "DEPOSITARY" means the clearing agency registered under the Exchange
Act that is designated to act as the Depositary for the Global Debentures. The
Depository Trust Company shall be the initial Depositary, until a successor
shall have been appointed and become such pursuant to the applicable provisions
of this Indenture, and thereafter, "DEPOSITARY" shall mean or include such
successor.

          "DESIGNATED SENIOR DEBT" means, with respect to the Company,
indebtedness under the Senior Credit Facility and any other Senior Debt in which
the instrument creating or evidencing the same or the assumption or guarantee
thereof (or related agreements or documents to which the Company is a party)
expressly provides that such Senior Debt shall be "Designated Senior Debt" for
purposes of this Indenture.

          "DETERMINATION DATE" has the meaning specified in Section 15.05(l).

          "EFFECTIVE DATE" has the meaning specified in Section 3.05(d).

          "EVENT OF DEFAULT" has the meaning specified in Section 6.01.

          "EXCHANGE ACT" means the Securities Exchange Act of 1934, as amended,
and the rules and regulations promulgated thereunder, as in effect from time to
time.

                                        5
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          "EX DIVIDEND DATE" means, with respect to any issuance or distribution
on shares of Common Stock, the first date on which a sale of shares of Common
Stock does not automatically transfer the right to receive the relevant
distribution from the seller of the shares to the buyer.

          "EXPIRATION TIME" means the last time tenders or exchanges may be made
pursuant to a tender or exchange offer.

          "FINAL NOTICE DATE" has the meaning specified in Section 15.02(g).

          "FORM OF CONVERSION NOTICE" has the meaning specified in Section
15.02(a).

          "FUNDAMENTAL CHANGE" means the occurrence after the Original Issuance
Date of any of the following:

          (a)    any "person" (as such term is used in Sections 13(d) and 14(d)
of the Exchange Act) is or becomes the "beneficial owner" (as defined in Rules
13d-3 and 13d-5 under the Exchange Act, except that for purposes of this clause
(a) such person shall be deemed to have "beneficial ownership" of all shares
that any such person has the right to acquire, whether such right is exercisable
immediately or only after the passage of time), directly or indirectly, of more
than 50% of the total voting power of the voting stock of the Company (for the
purposes of this clause (a), such person shall be deemed to beneficially own any
voting stock of a person (the "specified person") held by any other person (the
"parent entity"), if such other person is the beneficial owner (as defined in
this clause (a)), directly or indirectly, of more than 50% of the voting power
of the voting stock of such parent entity); or

          (b)    individuals who on the Original Issuance Date, constituted the
Board of Directors of the Company (together with any new directors whose
election by the Board of Directors of the Company or whose nomination for
election by the stockholders of the Company was approved by a vote of 51% of the
directors of the Company then still in office who were either directors on the
Original Issuance Date or whose election or nomination for election was
previously so approved) cease for any reason to constitute a majority of the
Board of Directors of the Company then in office;

          (c)    the adoption of a plan relating to the liquidation or
dissolution of the Company; or

          (d)    the merger or consolidation of the Company with or into another
Person, or the merger of another Person with the Company, or the sale of all or
substantially all the assets of the Company (in each case, determined on a
consolidated basis) to another Person, other than a transaction following which
(A) in the case of a merger or consolidation transaction, holders of securities
that represented 100% of the voting stock of the Company immediately prior to
such transaction (or other securities into which such securities are converted
as part of such merger or consolidation transaction) hold directly or indirectly
at least a majority of the voting power of the voting stock of the surviving
Person in such merger or consolidation transaction immediately after such
transaction and in substantially the same proportion as before such merger or
consolidation transaction and (B) in the case of a sale of assets transaction,
(i) the transferee Person(s) become(s) a guarantor in respect of the Debentures
and (ii) either (x) the transferee

                                        6
<Page>

Person(s) constitute(s) a subsidiary of the transferor(s) of such assets or (y)
holders of securities that represented 100% of the voting stock of the Company
immediately prior to such sale of assets transaction hold, directly or
indirectly, at least a majority of the voting power of the voting stock of the
transferee Person(s) in such sale of assets transaction immediately after such
sale of assets transaction and in substantially the same proportion as before
such sale of assets transaction; or

          (e)    the capital stock of the Company or other capital stock into
which the Debentures are convertible is neither listed for trading on a United
States national or regional securities exchange nor approved for listing on the
Nasdaq National Market or any similar United States system of automated
dissemination of quotations of securities prices, and no American Depositary
Shares or similar instruments for such capital stock are so listed or approved
for listing in the United States.

          Notwithstanding anything to the contrary, a Fundamental Change will
not be deemed to have occurred in respect of the occurrence of an event
described in clause (a), (b), (c) or (d), however, if at least 90% of the
consideration, excluding cash payments for fractional shares, in the transaction
or transactions constituting the Fundamental Change consists of shares of
capital stock traded on a United States national or regional securities exchange
or quoted on the Nasdaq National Market or any similar United States system of
automated dissemination of quotations of securities prices, or which will be so
traded or quoted when issued or exchanged in connection with a Fundamental
Change (these securities being referred to as "Publicly Traded Securities") and
as a result of the transaction or transactions the Debentures become convertible
into such Publicly Traded Securities, excluding cash payments for fractional
shares, such Publicly Traded Securities to be valued as of the date on which the
transaction or transactions constituting the Fundamental Change are publicly
announced.

          "FUNDAMENTAL CHANGE REPURCHASE DATE" has the meaning specified in
Section 3.05(a).

          "FUNDAMENTAL CHANGE REPURCHASE ELECTION" has the meaning specified in
Section 3.05(c)(i).

          "FUNDAMENTAL CHANGE REPURCHASE NOTICE" has the meaning specified in
Section 3.05(b).

          "FUNDAMENTAL CHANGE REPURCHASE PRICE" has the meaning specified in
Section 3.05(a).

          "GAAP" means generally accepted accounting principles in the United
States of America as in effect as of the Original Issuance Date, including those
set forth in:

                 (a)   the opinions and pronouncements of the Accounting
          Principles Board of the American Institute of Certified Public
          Accountants;

                 (b)   statements and pronouncements of the Financial Accounting
          Standards Board;

                                        7
<Page>

                 (c)   such other statements by such other entities as approved
          by a significant segment of the accounting profession; and

                 (d)   the rules and regulations of the Commission governing the
          inclusion of financial statements (including pro forma financial
          statements) in periodic reports required to be filed pursuant to
          Section 13 of the Exchange Act, including opinions and pronouncements
          in staff accounting bulletins and similar written statements from the
          accounting staff of the Commission.

          All computations based on GAAP contained in this Indenture shall be
computed in conformity with GAAP.

          "GLOBAL DEBENTURE" means a Debenture in global form registered in the
name of the Depository or the nominee of the Depository.

          "INCUR" means issue, assume, guarantee, incur or otherwise become
liable for, and the term "INCURRENCE" when used as a noun shall have a
correlative meaning.

          "INDEBTEDNESS" means, with respect to any Person, on any date of
determination (without duplication):

                 (a)   obligations of such Person for borrowed money, or
          evidenced by bonds, debentures, notes or similar instruments, for
          which such Person is responsible or liable;

                 (b)   obligations of such Person for the reimbursement of
          obligors on letters of credit, bank guarantees or bankers' acceptances
          (other than obligations with respect to letters of credit, bank
          guarantees or bankers' acceptances entered into in the ordinary course
          of business of such Person, in each case, to the extent such letters
          of credit, bank guarantees or bankers' acceptances are not drawn upon
          or, if and to the extent drawn upon, such drawing is reimbursed no
          later than the tenth Business Day following payment of such letters of
          credit, bank guarantees or bankers' acceptances);

                 (c)   obligations of such Person in respect of leases required
          in conformity with GAAP to be accounted for as capitalized lease
          obligations;

                 (d)   obligations and other liabilities of such Person under
          any lease or related document in connection with the lease of real
          property that provides that such Person is contractually obligated to
          purchase or cause a third party to purchase the leased property and
          thereby guarantee a minimum residual value of the leased property to
          the lessor;

                 (e)   obligations of such Person with respect to an interest
          rate swap agreement, interest rate cap agreement or other financial
          agreement or arrangement designed to protect such Person against
          fluctuations in interest rates, or foreign exchange contract, currency
          swap agreement or other similar agreement designed to protect such
          Person against fluctuation in currency values;

                                        8
<Page>

                 (f)   obligations of other Persons of the type described in
          paragraphs (a) to (e) above in respect of which such Person is liable
          or responsible, directly or indirectly, including by means of any
          Guarantee; and

                 (g)   obligations of another Person of the type described in
          paragraphs (a) to (e) above secured by any mortgage, pledge, lien or
          other encumbrance existing on property which is owned or held by such
          Person;

in each case other than any account payable or other accrued current liability
or obligation of such Person incurred in the ordinary course of business
connection with the obtaining of materials or services. For purposes of
determining the amount of Indebtedness under Section 6.01, the principal or
notional amount thereof (as determined in accordance with GAAP) shall be used.

          "INDENTURE" means this instrument as originally executed or, if
amended or supplemented as herein provided, as so amended or supplemented.

          "INITIAL PURCHASERS" means J.P. Morgan Securities Inc., Piper Jaffray
& Co. and William Blair & Company, L.L.C.

          "INTEREST" means, when used with respect to the Debentures, any
interest payable under the terms of the Debentures, including Contingent
Interest, if any, and Additional Interest, if any, payable under the terms of
the Registration Rights Agreement.

          "INTEREST PAYMENT DATE" means June 15 and December 15 of each year,
commencing December 15, 2004.

          "INTEREST PERIOD" means the period from the Original Issuance Date to
December 14, 2004 and thereafter, any six-month period from June 15 to December
14 or from December 15 to June 14, commencing on or after December 15, 2004 and
ending before June 14, 2034.

          "LAST REPORTED SALE PRICE" of the Common Stock on any date means the
closing sale price per share (or, if no closing sale price is reported, the
average of the bid and asked prices or, if more than one in either case, the
average of the average bid and the average asked prices) on that date as
reported in composite transactions for the principal United States national or
regional securities exchange on which the Common Stock is traded or, if the
Common Stock is not listed on a United States national or regional securities
exchange, as reported by the Nasdaq National Market. If the Common Stock is not
listed for trading on a United States national or regional securities exchange
and not reported by the Nasdaq National Market on the relevant date, the "LAST
REPORTED SALE PRICE" will be the last quoted bid price for the Common Stock in
the over-the-counter market on the relevant date as reported by the National
Quotation Bureau Incorporated or any similar United States system of automated
dissemination of quotation of securities prices. If the Common Stock is not so
quoted, the "LAST REPORTED SALE PRICE" will be the average of the mid-point of
the last bid and asked prices for the Common Stock on the relevant date from
each of at least three independent nationally recognized investment banking
firms selected by the Company for this purpose. "LAST REPORTED SALE PRICE" of
any other security shall have a correlative meaning. The Last Reported Sale
Price of the Common Stock shall be determined by the Company.

                                        9
<Page>

          "LIEN" means, with respect to any asset, any mortgage, lien, pledge,
charge, security interest or encumbrance of any kind in respect of such asset
given to secure Indebtedness, whether or not filed, recorded or otherwise
perfected under applicable law (including any conditional sale or other title
retention agreement, any lease in the nature thereof, any option or other
agreement to sell or give a security interest in and any filing of or agreement
to give any financing statement under the Uniform Commercial Code (or equivalent
statutes) of any jurisdiction, in each case other than relating to any account
payable or other accrued current liability or obligation incurred in the
ordinary course of business in connection with the obtaining of materials or
services.

          "MAKE-WHOLE PREMIUM" has the meaning specified in Section 3.05(d).

          "MOODY'S" has the meaning specified in Section 15.06(a).

          "NON-ELECTING SHARE" has the meaning specified in Section 15.06.

          "OFFICER" means the Chairman of the Board, the Chief Executive
Officer, the Chief Operating Officer, the Chief Financial Officer, the
President, any Vice President (whether or not designated by a number or numbers
or word or words added before or after the title "Vice President"), the
Treasurer or the Secretary or an Assistant Secretary of the Company.

          "OFFICERS' CERTIFICATE", when used with respect to the Company, means
a certificate signed by any two of the Chairman of the Board, the Chief
Executive Officer, the Chief Operating Officer, the President, the Chief
Financial Officer, any Vice President (whether or not designated by a number or
numbers or word or words added before or after the title "Vice President"), the
Treasurer or the Secretary or Assistant Secretary of the Company.

          "OPINION OF COUNSEL" means an opinion in writing signed by legal
counsel, who may be an employee of or counsel to the Company.

          "ORIGINAL ISSUANCE DATE" means the date on which the Debentures are
first authenticated and delivered under this Indenture.

          "OUTSTANDING", when used with reference to Debentures and subject to
the provisions of Section 8.04, means, as of any particular time, all Debentures
authenticated and delivered by the Trustee under this Indenture, except:

     (a)  Debentures theretofore canceled by the Trustee or delivered to the
Trustee for cancellation;

     (b)  Debentures, or portions thereof, (i) for the redemption of which
monies in the necessary amount shall have been deposited in trust with the
Trustee or with any Paying Agent (other than the Company or a Wholly Owned
Subsidiary) and the Redemption Date of which has already passed or (ii) which
shall have been otherwise discharged in accordance with Article 12;

     (c)  Debentures in lieu of which, or in substitution for which, other
Debentures shall have been authenticated and delivered pursuant to the terms of
Section 2.08; and

                                       10
<Page>

     (d)  Debentures converted into Common Stock pursuant to Article 15 and
Debentures deemed not outstanding pursuant to Article 3.

          "PAYING AGENT" has the meaning specified in Section 2.04.

          "PAYMENT BLOCKAGE NOTICE" has the meaning set forth in Section
17.03(b).

          "PAYMENT BLOCKAGE PERIOD" has the meaning set forth in Section
17.03(b).

          "PAYMENT DEFAULT" has the meaning set forth in Section 17.03(a).

          "PERSON" means any corporation, association, partnership, limited
liability company, individual, joint venture, joint stock company, trust,
unincorporated organization or government, or any agency or political
subdivision thereof.

          "PREDECESSOR DEBENTURE" of any particular Debenture means every
previous Debenture evidencing all or a portion of the same debt as that
evidenced by such particular Debenture, and, for the purposes of this
definition, any Debenture authenticated and delivered under Section 2.08 in lieu
of a lost, destroyed or stolen Debenture shall be deemed to evidence the same
debt as the lost, destroyed or stolen Debenture that it replaces.

          "PRINCIPAL VALUE CONVERSION" has the meaning specified in Section
15.01(a).

          "PURCHASE AGREEMENT" means the Purchase Agreement, dated June 15,
2004, between the Company and the Initial Purchasers, as amended from time to
time in accordance with its terms.

          "REDEMPTION" has the meaning specified in Section 3.01.

          "REDEMPTION DATE" has the meaning specified in Section 3.01.

          "REDEMPTION NOTICE" has the meaning specified in Section 3.02(a).

          "REDEMPTION PRICE" has the meaning specified in Section 3.01.

          "REGISTRATION RIGHTS AGREEMENT" means the Resale Registration Rights
Agreement, dated as of June 21, 2004, between the Company and the Initial
Purchasers, as amended from time to time in accordance with its terms.

          "REGULAR RECORD DATE" means, with respect to each Interest Payment
Date, the close of business on the June 1 or December 1 preceding such Interest
Payment Date (whether or not a Business Day).

          "REPURCHASE DATE" means the Fundamental Change Repurchase Date or the
Company Repurchase Date, as the context requires.

          "REPURCHASE ELECTION" means the Fundamental Change Repurchase Election
or the Company Repurchase Election, as the context requires.

                                       11
<Page>

          "REPURCHASE NOTICE" means the Fundamental Change Repurchase Notice or
the Company Repurchase Notice, as the context requires.

          "REPURCHASE PRICE" means the Fundamental Change Repurchase Price or
the Company Repurchase Price, as the context requires.

          "RESTRICTED SECURITIES" refers to every Debenture or Common Stock that
bears or is required under Section 2.07 to bear the legend set forth in Appendix
A.

          "RULE 144A" means Rule 144A as promulgated under the Securities Act.

          "SECURITIES ACT" means the Securities Act of 1933, as amended.

          "SENIOR CREDIT FACILITY" means the Loan Agreement dated as of January
14, 2004, between the Company and Citizens Bank of Massachusetts, together with
the related documents thereto (including the revolving loans thereunder and any
security documents), as amended, extended, renewed, restated, supplemented or
otherwise modified (in whole or in part, and without limitation as to amount,
terms, conditions, covenants and other provisions) from time to time.

          "SENIOR DEBT" means, with respect to the Company, the principal of,
premium, if any, and interest on (including interest accruing after, or which
would accrue but for the filing of a petition initiating any proceeding pursuant
to Bankruptcy Law at the rate specified in the applicable Senior Debt, whether
or not a claim for such interest would be allowed), all Indebtedness of the
Company arising under the Senior Credit Facility and all other secured
Indebtedness in which the instrument creating or evidencing the same or the
assumption or guarantee thereof expressly provides that such Indebtedness is
senior to the Debentures, whether outstanding on the date of the Indenture or
thereafter created, incurred, assumed or guaranteed by the Company (including
all deferrals, renewals, extensions or refundings of, or amendments,
modifications or supplements to the foregoing); PROVIDED, HOWEVER, that Senior
Debt does not include:

                 (a)   Indebtedness evidenced by the Debentures;

                 (b)   Indebtedness of the Company to any subsidiary of the
          Company;

                 (c)   any liability for federal, state, foreign, local or other
          taxes owed or owing by the Company;

                 (d)   accounts payable or other liabilities of the Company to
          trade creditors arising in the ordinary course of business; and

                 (e)   any other Indebtedness in which the instrument creating
          or evidencing the same or the assumption or guarantee thereof
          expressly provides that such Indebtedness is pari passu with, or is
          subordinated to, the Debentures.

          "SPIN-OFF" has the meaning specified in Section 15.05(c).

                                       12
<Page>

          "STANDARD & POOR'S" has the meaning specified in Section 15.06(a).

          "STATED MATURITY" means June 15, 2034.

          "STOCK PRICE" has the meaning specified in Section 3.05(d).

          "STOCK RECORD DATE" means, with respect to any dividend, distribution
or other transaction or event in which the holders of Common Stock have the
right to receive any cash, securities or other property or in which the Common
Stock (or other applicable security) is exchanged for or converted into any
combination of cash, securities or other property, the date fixed for
determination of stockholders entitled to receive such cash, securities or other
property (whether such date is fixed by the Board of Directors or by statute,
contract or otherwise).

          "SUBSIDIARY" means, with respect to any Person, (a) any corporation,
association or other business entity of which more than 50% of the total voting
power of shares of capital stock or other equity interest entitled (without
regard to the occurrence of any contingency) to vote in the election of
directors, managers or trustees thereof is at the time owned or controlled,
directly or indirectly, by such Person or one or more of the other subsidiaries
of that Person (or a combination thereof) and (b) any partnership (i) the sole
general partner or managing general partner of which is such Person or a
subsidiary of such Person or (ii) the only general partners of which are such
Person or of one or more subsidiaries of such Person (or any combination
thereof).

          "SUCCESSOR COMPANY" has the meaning specified in Section 11.01(a).

          "TRADING DAY" means a day during which trading in securities generally
occurs on the New York Stock Exchange or, if the applicable security is not
listed on the New York Stock Exchange, on the principal other national or
regional securities exchange on which the applicable security is then listed or,
if the applicable security is not listed on a national or regional securities
exchange, on the National Association of Securities Dealers Automated Quotation
System or, if the applicable security is not quoted on the National Association
of Securities Dealers Automated Quotation System, on the principal other market
on which the applicable security is then traded (provided that no day on which
trading of the applicable security is suspended on such exchange or other
trading market will count as a Trading Day).

          "TRADING PRICE" means, as of any date of determination, the average of
the secondary market bid quotations obtained by the Trustee for $2,000,000
principal amount of Debentures at approximately 3:30 p.m., New York City time,
on such determination date from three independent nationally recognized
securities dealers (none of which shall be the Company or an Affiliate thereof)
in The City of New York (or such other place that may be determined from time to
time by the Company) selected by the Company; PROVIDED, HOWEVER, if at least
three such bids cannot reasonably be obtained by the Trustee, but two such bids
are obtained, then the average of the two bids shall be used, and if only one
such bid can reasonably be obtained by the Trustee, that one bid shall be used.
If the Trustee cannot reasonably obtain at least one bid for $2,000,000
principal amount of Debentures from an independent nationally recognized
securities dealer, then the Trading Price per $1,000 principal amount of
Debentures will be deemed to be (a) with respect to any conversion of Debentures
pursuant to Section 15.01(a)(iv), less than 98%

                                       13
<Page>

of the product of (i) the Last Reported Sale Price of the Common Stock and (ii)
the Conversion Rate and (b) with respect to any determination of Contingent
Interest pursuant to Section 14.01, the product of (i) the average of the Last
Reported Sale Price of the Common Stock on the five (5) Trading Days ending on
such determination date and (ii) the Conversion Rate.

          "TRUST INDENTURE ACT" means the Trust Indenture Act of 1939, as
amended, as it was in force at the date of this Indenture, except as provided in
Sections 10.03 and 15.06; PROVIDED that if the Trust Indenture Act of 1939 is
amended after the date hereof, the term "Trust Indenture Act" shall mean, to the
extent required by such amendment, the Trust Indenture Act of 1939 as so
amended.

          "TRUST OFFICER" means, when used with respect to the Trustee, any
officer within the corporate trust department of the Trustee to whom any
corporate trust matter is referred because of such person's knowledge of and
familiarity with the particular subject and who shall have direct responsibility
for the administration of this Indenture.

          "TRUSTEE" means U.S. Bank National Association, and its successors and
any corporation resulting from or surviving any consolidation or merger to which
it or its successors may be a party and any successor trustee at the time
serving as successor trustee hereunder.

          "UNIFORM COMMERCIAL CODE" means the New York Uniform Commercial Code
as in effect from time to time.

          "VOTING STOCK" of a Person means all classes of capital stock or other
interests (including partnership interests) of such Person then outstanding and
normally entitled (without regard to the occurrence of any contingency) to vote
in the election of directors, managers or trustees thereof.

          "WHOLLY OWNED SUBSIDIARY" means a subsidiary of the Company all the
capital stock of which (other than directors' qualifying or other legally
required shares) is owned by the Company or another Wholly Owned Subsidiary.

                                    ARTICLE 2
     ISSUE, DESCRIPTION, EXECUTION, REGISTRATION AND EXCHANGE OF DEBENTURES

          SECTION 2.01.  AMOUNT OF DEBENTURES. The aggregate principal amount
of Debentures which may be authenticated and delivered under this Indenture
shall not exceed $75,000,000 (or up to $90,000,000 if the Initial Purchasers'
option to purchase additional Debentures set forth in the Purchase Agreement is
exercised in full) (except for Debentures authenticated and delivered upon
registration of transfer of, or in exchange for, or in lieu of, other Debentures
pursuant to Sections 2.07, 2.08, 2.09, 2.10, 3.03, 15.02 or Appendix A).

          SECTION 2.02.  FORM AND DATING. Provisions relating to the Debentures
are set forth in Appendix A, which is hereby incorporated in and expressly made
a part of this Indenture. The Debentures and the Trustee's certificate of
authentication shall each be substantially in the form of Exhibit A hereto,
which is hereby incorporated in and expressly made a part of this Indenture. The
Debentures may have notations, legends or endorsements required by law, stock
exchange rule, agreements to which the Company is subject, if any, or

                                       14
<Page>

usage (PROVIDED that any such notation, legend or endorsement is in a form
acceptable to the Company). Each Debenture shall be dated the date of its
authentication. The Debentures shall be issuable only in registered form without
interest coupons and only in denominations of $1,000 and integral multiples
thereof.

          SECTION 2.03.  EXECUTION AND AUTHENTICATION. Two Officers shall sign
the Debentures for the Company by manual or facsimile signature.

          If an Officer whose signature is on a Debenture no longer holds that
office at the time the Trustee authenticates the Debenture, the Debenture shall
be valid nevertheless.

          A Debenture shall not be valid until an authorized signatory of the
Trustee manually signs the certificate of authentication on the Debenture. The
signature shall be conclusive evidence that the Debenture has been authenticated
under this Indenture.

          The Trustee shall authenticate and make available for delivery
Debentures as set forth in Appendix A.

          The Trustee may appoint an authenticating agent reasonably acceptable
to the Company to authenticate the Debentures. Any such appointment shall be
evidenced by an instrument signed by a Trust Officer, a copy of which shall be
furnished to the Company. Unless limited by the terms of such appointment, an
authenticating agent may authenticate Debentures whenever the Trustee may do so.
Each reference in this Indenture to authentication by the Trustee includes
authentication by such agent. An authenticating agent has the same rights as any
Debenture Registrar, Paying Agent or agent for service of notices and demands.

          SECTION 2.04.  DEBENTURE REGISTRAR AND PAYING AGENT. (a) The Company
shall maintain an office or agency where Debentures may be presented for
registration of transfer or for exchange (the "DEBENTURE REGISTRAR") and an
office or agency where Debentures may be presented for payment (the "PAYING
AGENT"). The Debenture Registrar shall keep a register of the Debentures and of
their transfer and exchange (the "DEBENTURE REGISTER"). The Company may have one
or more co-debenture registrars and one or more additional paying agents. The
term "Paying Agent" includes any additional paying agent, and the term
"Debenture Registrar" includes any co-debenture registrars. The Company
initially appoints the Trustee as (i) Debenture Registrar and Paying Agent in
connection with the Debentures and (ii) the Custodian with respect to the Global
Debentures.

          (b) The Company shall enter into an appropriate agency agreement with
any Debenture Registrar or Paying Agent not a party to this Indenture, which
shall incorporate the terms of the Trust Indenture Act. The agreement shall
implement the provisions of this Indenture that relate to such agent. The
Company shall notify the Trustee of the name and address of any such agent. If
the Company fails to maintain a Debenture Registrar or Paying Agent, the Trustee
shall act as such and shall be entitled to appropriate compensation therefor
pursuant to Section 7.06. The Company may change the Paying Agent or Debenture
Registrar without prior notice to the holders of the Debentures. The Company or
any domestically organized Wholly Owned Subsidiary may act as Paying Agent or
Debenture Registrar.

                                       15
<Page>

          (c) The Company may remove any Debenture Registrar or Paying Agent
upon written notice to such Debenture Registrar or Paying Agent and to the
Trustee; PROVIDED, however, that no such removal shall become effective until
(i) acceptance of an appointment by a successor as evidenced by an appropriate
agreement entered into by the Company and such successor Debenture Registrar or
Paying Agent, as the case may be, and delivered to the Trustee or (ii)
notification to the Trustee that the Trustee shall serve as Debenture Registrar
or Paying Agent until the appointment of a successor in accordance with clause
(i) above. The Debenture Registrar or Paying Agent may resign at any time upon
written notice to the Company and the Trustee.

          SECTION 2.05.  PAYING AGENT TO HOLD MONEY IN TRUST. By at least
10:00 a.m (New York City time) on the date on which any principal of and
interest on any Debenture is due and payable, the Company shall deposit with the
Paying Agent (or if the Company or a Wholly Owned Subsidiary is acting as Paying
Agent, segregate and hold in trust for the benefit of the Persons entitled
thereto (or, in the case of a Wholly Owned Subsidiary, the Company shall cause
such Wholly Owned Subsidiary to so segregate and hold such funds)) a sum
sufficient to pay such principal and interest when so becoming due. The Company
shall require each Paying Agent (other than the Trustee) to agree in writing
that the Paying Agent shall hold in trust for the benefit of holders or the
Trustee all money held by the Paying Agent for the payment of principal of and
interest on the Debentures and shall notify the Trustee of any default by the
Company in making any such payment. If the Company or a Wholly Owned Subsidiary
acts as Paying Agent, it shall segregate the money held by it as Paying Agent
and hold it as a separate trust fund (or, in the case of a Wholly Owned
Subsidiary, the Company shall cause such Wholly Owned Subsidiary to so segregate
and hold such funds). The Company at any time may require a Paying Agent to pay
all money held by it to the Trustee and to account for any funds disbursed by
the Paying Agent. Upon complying with this Section, the Paying Agent shall have
no further liability for the money delivered to the Trustee.

          SECTION 2.06.  HOLDER LISTS. The Trustee shall preserve in as current
a form as is reasonably practicable the most recent list available to it of the
names and addresses of holders. If the Trustee is not the Debenture Registrar,
the Company shall furnish, or cause the Debenture Registrar to furnish, to the
Trustee, in writing at least five Business Days before each interest payment
date and at such other times as the Trustee may request in writing within
fifteen (15) days, a list in such form and as of such date as the Trustee may
reasonably require of the names and addresses of holders.

          SECTION 2.07.  TRANSFER AND EXCHANGE. The Debentures shall be issued
in registered form and shall be transferable only upon the surrender of a
Debenture for registration of transfer and in compliance with Appendix A. When a
Debenture is presented to the Debenture Registrar with a request to register a
transfer, the Debenture Registrar shall register the transfer as requested if
its requirements therefor are met. When Debentures are presented to the
Debenture Registrar with a request to exchange them for an equal principal
amount of Debentures of other denominations, the Debenture Registrar shall make
the exchange as requested if the same requirements are met. To permit
registration of transfers and exchanges, the Company shall execute and the
Trustee shall authenticate Debentures at the Debenture Registrar's request. The
Company may require payment of a sum sufficient to pay all taxes, assessments or
other governmental charges in connection with any transfer or exchange pursuant

                                       16
<Page>

to this Section. The Company shall not be required to make and the Debenture
Registrar need not register transfers or exchanges of Debentures selected for
redemption (except, in the case of Debentures to be redeemed in part, the
portion thereof not to be redeemed) or any Debentures for a period of 15 days
before a selection of Debentures to be redeemed.

          Prior to the due presentation for registration of transfer of any
Debenture, the Company, the Trustee, the Paying Agent and the Debenture
Registrar may deem and treat the Person in whose name a Debenture is registered
as the absolute owner of such Debenture for the purpose of receiving payment of
principal of and interest, if any, on such Debenture and for all other purposes
whatsoever, whether or not such Debenture is overdue, and none of the Company,
the Trustee, the Paying Agent, or the Debenture Registrar shall be affected by
notice to the contrary.

          Any holder of a Global Debenture shall, by acceptance of such Global
Debenture, agree that transfers of beneficial interest in such Global Debenture
may be effected only through a book-entry system maintained by (a) the holder of
such Global Debenture (or its agent) or (b) any holder of a beneficial interest
in such Global Debenture, and that ownership of a beneficial interest in such
Global Debenture shall be required to be reflected in a book entry.

          All Debentures issued upon any transfer or exchange pursuant to the
terms of this Indenture shall evidence the same debt and shall be entitled to
the same benefits under this Indenture as the Debentures surrendered upon such
transfer or exchange.

          The Trustee shall have no obligation or duty to monitor, determine or
inquire as to compliance with any restrictions on transfer imposed under this
Indenture or under applicable law with respect to any transfer of any interest
in any Debenture (including any transfer between or among Depositary
Participants or beneficial owners of interests in any Global Debenture) other
than to require delivery of such certificates and other documentation or
evidence as are expressly required by, and to do so if and when expressly
required by the terms of, this Indenture, and to examine the same to determine
substantial compliance as to form with the express requirements hereof.

          SECTION 2.08.  REPLACEMENT DEBENTURES. If a mutilated Debenture is
surrendered to the Debenture Registrar or if the holder of a Debenture claims
that the Debenture has been lost, destroyed or wrongfully taken, the Company
shall issue and the Trustee shall authenticate a replacement Debenture if the
requirements of Section 8-405 of the Uniform Commercial Code are met, such that
the holder (a) satisfies the Company and the Trustee as to compliance with such
requirements within a reasonable time after such holder has notice of such loss,
destruction or wrongful taking and the Debenture Registrar does not register a
transfer prior to receiving such notification, (b) makes such request to the
Company or the Trustee prior to the Debenture being acquired by a protected
purchaser as defined in Section 8 303 of the Uniform Commercial Code (a
"protected purchaser") and (c) satisfies any other reasonable requirements of
the Trustee. If required by the Trustee or the Company, such holder shall
furnish an indemnity bond sufficient in the judgment of the Company and the
Trustee to protect the Company, the Trustee, the Paying Agent and the Debenture
Registrar from any loss that any of them may suffer if a Debenture is replaced.
The Company and the Trustee may charge the holder for their expenses in
replacing a Debenture and may require the payment of a sum

                                       17
<Page>

sufficient to cover any fax or other governmental change that may be imposed in
relation thereto. In the event any such mutilated, lost, destroyed or wrongfully
taken Debenture has become or is about to become due and payable, the Company in
its discretion may pay such Debenture instead of issuing a new Debenture in
replacement thereof.

          Every replacement Debenture is an additional obligation of the
Company.

          The provisions of this Section 2.08 are exclusive and shall preclude
(to the extent lawful) all other rights and remedies with respect to the
replacement or payment of mutilated, lost, destroyed or wrongfully taken
Debentures.

          SECTION 2.09.  OUTSTANDING DEBENTURES. Debentures outstanding at any
time are all Debentures authenticated by the Trustee except for those canceled
by it, those delivered to it for cancellation and those described in this
Section as not outstanding. Subject to Section 8.04, a Debenture does not cease
to be outstanding because the Company or an Affiliate of the Company holds the
Debenture.

          If a Debenture is replaced pursuant to Section 2.08, it ceases to be
outstanding unless the Trustee and the Company receive proof satisfactory to
them that the replaced Debenture is held by a protected purchaser.

          If the Paying Agent segregates and holds in trust, in accordance with
this Indenture, on a redemption date or maturity date money sufficient to pay
all principal and interest payable on that date with respect to the Debentures
(or portions thereof) to be redeemed or maturing, as the case may be, then on
and after that date such Debentures (or portions thereof) cease to be
outstanding and interest on them ceases to accrue.

          SECTION 2.10.  TEMPORARY DEBENTURES. In the event that Definitive
Debentures are to be issued under the terms of this Indenture, until such
Definitive Debentures are ready for delivery, the Company may prepare and the
Trustee shall authenticate temporary Debentures. Temporary Debentures shall be
substantially in the form of Definitive Debentures but may have variations that
the Company considers appropriate for temporary Debentures. Without unreasonable
delay, the Company shall prepare and the Trustee shall authenticate Definitive
Debentures and deliver them in exchange for temporary Debentures upon surrender
of such temporary Debentures at the office or agency of the Company maintained
for this purpose, without charge to the holder.

          SECTION 2.11.  CANCELLATION. The Company at any time may deliver
Debentures to the Trustee for cancellation. The Debenture Registrar and the
Paying Agent shall forward to the Trustee any Debentures surrendered to them for
registration of transfer, exchange or payment. The Trustee and no one else shall
cancel all Debentures surrendered for registration of transfer, exchange,
payment or cancellation and shall dispose of canceled Debentures in accordance
with its customary procedures or deliver canceled Debentures to the Company
pursuant to written direction by an Officer. The Company may not issue new
Debentures to replace Debentures it has redeemed, paid or delivered to the
Trustee for cancellation. The Trustee shall not authenticate Debentures in place
of canceled Debentures other than pursuant to the terms of this Indenture.

                                       18
<Page>

          SECTION 2.12.  DEFAULTED INTEREST. If the Company defaults in a
payment of interest (including Contingent Interest and Additional Interest, if
any) on the Debentures, the Company shall pay the defaulted interest (plus
interest on such defaulted interest at the rate borne by the Debentures plus 1%
per annum to the extent lawful) in any lawful manner. The Company may pay the
defaulted interest to the Persons who are holders on a subsequent special record
date. The Company shall fix or cause to be fixed any such special record date
and payment date to the reasonable satisfaction of the Trustee and shall
promptly mail or cause to be mailed to each holder a notice that states the
special record date, the payment date and the amount of defaulted interest to be
paid.

          SECTION 2.13.  CUSIP AND ISIN NUMBERS. The Company in issuing the
Debentures may use "CUSIP" and ISIN numbers (if then generally in use) and, if
so, the Trustee shall use "CUSIP" and ISIN numbers in notices of redemption as a
convenience to holders; PROVIDED, HOWEVER, that any such notice may state that
no representation is made as to the correctness of such numbers either as
printed on the Debentures or as contained in any notice of a redemption and that
reliance may be placed only on the other identification numbers printed on the
Debentures, and any such redemption shall not be affected by any defect in or
omission of such numbers. The Company shall promptly notify the Trustee of any
change in the "CUSIP" numbers.

                                    ARTICLE 3
                     REDEMPTION AND REPURCHASE OF DEBENTURES

          SECTION 3.01.  REDEMPTION. The Debentures will not be redeemable at
the Company's option prior to June 20, 2011. At any time on or after June 20,
2011 and prior to Stated Maturity, the Company, at its option, may redeem, in
whole or in part, the Debentures in accordance with the provisions of Sections
3.02, 3.03 and 3.04 on the date of redemption (the "REDEMPTION DATE") for cash,
at a redemption price (the "REDEMPTION PRICE") equal to 100% of the principal
amount of the Debentures to be redeemed plus accrued and unpaid interest
(including Contingent Interest and Additional Interest, if any), if any, on the
Debentures to be redeemed to (but excluding) the Redemption Date (such
redemption, a "REDEMPTION").

          SECTION 3.02.  NOTICE OF REDEMPTION; SELECTION OF DEBENTURES. (a) In
case the Company shall desire to exercise the right to redeem all or, as the
case may be, any part of the Debentures pursuant to Section 3.01, it shall fix a
Redemption Date and it or, at its written request received by the Trustee not
fewer than forty five (45) days prior (or such shorter period of time as may be
acceptable to the Trustee) to the Redemption Date, the Trustee in the name of
and at the expense of the Company, shall mail or cause to be mailed a notice of
such redemption (a "REDEMPTION NOTICE") not fewer than thirty (30) nor more than
sixty (60) days prior to the Redemption Date to each holder of Debentures so to
be redeemed at its last address as the same appears on the Debenture Register;
PROVIDED that if the Company shall give such notice, it shall also give written
notice of the Redemption Date to the Trustee. Such mailing shall be by first
class mail. The notice, if mailed in the manner herein provided, shall be
conclusively presumed to have been duly given, whether or not the holder
receives such notice. In any case, failure to give such notice by mail or any
defect in the notice to the holder of any Debenture designated for redemption
shall not affect the validity of the proceedings for the redemption of any other
Debenture. Concurrently with the mailing of any such Redemption Notice, the
Company shall

                                       19
<Page>

issue a press release announcing such redemption, the form and content of which
press release shall be determined by the Company in its sole discretion. The
failure to issue any such press release or any defect therein shall not affect
the validity of the Redemption Notice or any of the proceedings for the
redemption of any Debenture (or portion thereof) called for redemption.

          (b) Each such Redemption Notice shall specify the aggregate principal
amount of Debentures to be redeemed, the CUSIP number or numbers of the
Debentures being redeemed, the Redemption Date (which shall be a Business Day),
the Redemption Price at which Debentures are to be redeemed, the place or places
of payment, that payment will be made upon presentation and surrender of such
Debentures, that interest accrued to the Redemption Date will be paid as
specified in said notice, and that on and after said date interest thereon or on
the portion thereof to be redeemed will cease to accrue. Such notice shall also
state the current Conversion Rate, the date on which the right to convert such
Debentures or portions thereof into Common Stock will expire (which date shall
not be later than the close of business on the second Business Day prior to the
Redemption Date), whether the Company has elected to satisfy all or a portion of
its Conversion Obligation with cash in lieu of delivery of shares of Common
Stock with respect to any Debentures (or portions thereof) to be redeemed and,
if the Company has determined to satisfy all or any portion of the Conversion
Obligation in cash, the dollar amount of the Conversion Obligation to be
satisfied in cash (which must be expressed either as 100% of the Conversion
Obligation or as a fixed dollar amount). In case any Debenture is to be redeemed
in part, the Redemption Notice shall state the portion of the principal amount
of the Debentures to be redeemed and shall state that, on and after the
Redemption Date, upon surrender of such Debenture, a new Debenture or Debentures
in principal amount equal to the unredeemed portion thereof will be issued.

          (c) On or prior to the Redemption Date specified in the Redemption
Notice given as provided in this Section 3.02, the Company will deposit with the
Trustee or with one or more Paying Agents (or, if the Company or any Wholly
Owned Subsidiary is acting as Paying Agent, set aside, segregate and hold in
trust as provided in Section 4.04) an amount of money in immediately available
funds sufficient to redeem on the Redemption Date all the Debentures (or
portions thereof) so called for redemption (other than those theretofore
surrendered for conversion into Common Stock) at the applicable Redemption
Price; PROVIDED that if such payment is made on the Redemption Date, it must be
received by the Trustee or Paying Agent, as the case may be, by 10:00 a.m., New
York City time, on such date. The Company shall be entitled to retain any
interest, yield or gain on amounts deposited with the Trustee or any Paying
Agent pursuant to this Section 3.02(c) in excess of amounts required hereunder
to pay the Redemption Price (PROVIDED, HOWEVER, that the Trustee shall not be
under any obligation to invest or otherwise pay interest on any such amounts
deposited with it unless and except to the extent otherwise expressly agreed in
writing between the Trustee and the Company). If any Debenture (or portion
thereof) called for redemption is converted pursuant hereto prior to such
Redemption Date, any money deposited with the Trustee or any Paying Agent or so
set aside, segregated and held in trust for the redemption of such Debenture
shall be paid to the Company upon its written request, or, if then held by the
Company or any Wholly Owned Subsidiary, shall be discharged from such trust.
Whenever any Debentures are to be redeemed, the Company will give the Trustee
written notice in the form of an Officers' Certificate not fewer than forty-five
(45) days (or such shorter period of time as may be acceptable to the Trustee)
prior to the Redemption Date as to the aggregate principal amount of Debentures
to be redeemed.

                                       20
<Page>

          (d) If less than all of the outstanding Debentures are to be redeemed,
the Trustee shall select the Debentures or portions thereof of the Global
Debenture or the Debentures in certificated form to be redeemed (in principal
amounts of $1,000 or integral multiples thereof) by lot, on a pro rata basis or
by another method the Trustee considers fair and appropriate. If any Debenture
selected for partial redemption is submitted for conversion in part after such
selection, the portion of such Debenture submitted for conversion shall be
deemed (so far as may be possible) to be from, and to include, the portion
selected for redemption. The Debentures (or portions thereof) so selected shall
be deemed duly selected for redemption for all purposes hereof, notwithstanding
that any such Debenture is submitted for conversion in part before the mailing
of the Redemption Notice.

          Upon any redemption of less than all of the outstanding Debentures,
the Company and the Trustee may (but need not), solely for purposes of
determining the pro rata allocation among such Debentures as are unconverted and
outstanding at the time of redemption, treat as outstanding any Debentures
surrendered for conversion during the period of fifteen (15) days next preceding
the mailing of a Redemption Notice and may (but need not) treat as outstanding
any Debenture authenticated and delivered during such period in exchange for the
unconverted portion of any Debenture converted in part during such period.

          SECTION 3.03.  PAYMENT OF DEBENTURES CALLED FOR REDEMPTION BY THE
COMPANY. If notice of redemption has been given as provided in Section 3.03,
the Debentures (or portions thereof) with respect to which such notice has been
given shall, unless converted into Common Stock pursuant to the terms hereof,
become due and payable on the Redemption Date and at the place or places stated
in such notice at the applicable Redemption Price, and on and after the
Redemption Date (unless the Company shall default in the payment of such
Debentures at the Redemption Price) interest (including Contingent Interest and
Additional Interest, if any) on the Debentures (or portions thereof) so called
for redemption shall cease to accrue and, after the close of business on the
second Business Day immediately preceding the Redemption Date (unless the
Company shall default in the payment of such Debentures at the Redemption
Price), such Debentures (or portions thereof) shall cease to be convertible into
Common Stock and to be entitled to any benefit or security under this Indenture,
and the holders thereof shall have no right in respect of such Debentures (or
portions thereof) except the right to receive the Redemption Price thereof
pursuant to this Indenture. On presentation and surrender of such Debentures at
a place of payment specified in said notice, the said Debentures or the
specified portions thereof shall be paid and redeemed by the Company at the
applicable Redemption Price; PROVIDED that if the applicable Redemption Date is
after a record date but on, or before, an Interest Payment Date, the interest
(including Contingent Interest and Additional Interest, if any) payable on such
Interest Payment Date shall be paid on such Interest Payment Date to the holders
of record of such Debentures on the applicable Regular Record Date instead of
the holders surrendering such Debentures (or portions thereof) for redemption on
such date.

          Upon presentation of any Debenture redeemed in part only, the Company
shall execute and the Trustee shall authenticate and make available for delivery
to the holder thereof, at the expense of the Company, a new Debenture or
Debentures, of authorized denominations, in principal amount equal to the
unredeemed portion of the Debentures so presented.

                                       21
<Page>

          Notwithstanding the foregoing, the Trustee shall not redeem any
Debentures or mail any Redemption Notice during the continuance of a default in
payment of interest (including Contingent Interest and Additional Interest, if
any) on the Debentures. If any Debenture (or portion thereof) called for
redemption shall not be so paid upon surrender thereof for redemption, the
principal shall, until paid or duly provided for, continue to bear interest at
the rate borne by the Debenture, compounded semiannually, and such Debenture
shall remain convertible into Common Stock until the principal and interest
shall have been paid or duly provided for. The Company will notify all of the
holders if the Company redeems any of the Debentures.

          SECTION 3.04.  CONVERSION ARRANGEMENT ON CALL FOR REDEMPTION. In
connection with any redemption of Debentures, the Company may arrange for the
purchase and conversion of any Debentures by an agreement with one or more
investment banks or other purchasers to purchase such Debentures by paying to
the Trustee in trust for the Debentureholders, on or before the Redemption Date,
an amount not less than the Redemption Price of such Debentures. Notwithstanding
anything to the contrary contained in this Article 3, the obligation of the
Company to pay the Redemption Price of such Debentures shall be deemed to be
satisfied and discharged to the extent such amount is so paid by such
purchasers. If such an agreement is entered into, a copy of which will be filed
with the Trustee prior to the Redemption Date, any Debentures not duly
surrendered for conversion by the holders thereof may, at the option of the
Company, be deemed, to the fullest extent permitted by law, acquired by such
purchasers from such holders and (notwithstanding anything to the contrary
contained in Article 15) surrendered by such purchasers for conversion, all as
of immediately prior to the close of business on the Redemption Date (and the
right to convert any such Debentures shall be extended through such time),
subject to payment of the above amount as aforesaid. At the direction of the
Company, the Trustee shall hold and dispose of any such amount paid to it in the
same manner as it would monies deposited with it by the Company for the
redemption of Debentures. Without the Trustee's prior written consent, no
arrangement between the Company and such purchasers for the purchase and
conversion of any Debentures shall increase or otherwise affect any of the
powers, duties, responsibilities or obligations of the Trustee as set forth in
this Indenture.

          SECTION 3.05.  REPURCHASE OF DEBENTURES BY THE COMPANY AT OPTION OF
HOLDERS UPON A FUNDAMENTAL CHANGE. (a) If a Fundamental Change shall occur at
any time prior to Stated Maturity, each holder shall have the right, at such
holder's option, to require the Company to repurchase for cash all of such
holder's Debentures, or any portion thereof that is equal to $1,000 principal
amount or an integral multiple thereof, on the date specified in the Fundamental
Change Repurchase Notice, which date shall not be later than thirty-five (35)
days after the occurrence of such Fundamental Change but in no event prior to
the date on which such Fundamental Change occurs (the "FUNDAMENTAL CHANGE
REPURCHASE DATE"). The Company shall repurchase such Debentures at a price (the
"FUNDAMENTAL CHANGE REPURCHASE PRICE") equal to 100% of the principal amount of
the Debentures to be repurchased plus accrued and unpaid interest (including
Contingent Interest and Additional Interest, if any), if any, to (but excluding)
the Fundamental Change Repurchase Date plus the Make-Whole Premium, if
applicable; PROVIDED that if such Fundamental Change Repurchase Date falls on an
Interest Payment Date, then the interest payable on such Interest Payment Date
shall be paid to the

                                       22
<Page>

holders of record of the Debentures on the applicable Record Date instead of the
holders surrendering the Debentures for repurchase on such date.

          The Company's obligation to repurchase all or a portion of a holder's
Debentures under this Section 3.05 shall be satisfied if (a) a third party makes
the offer to repurchase the Debentures at the Fundamental Change Repurchase
Price in the manner and at the times and otherwise in compliance in all material
respects with the requirements set out in this Section 3.05 and (b) such third
party (i) purchases all Debentures properly tendered and not withdrawn with
respect to the applicable Fundamental Change and (ii) otherwise complies with
the obligations of the Company in connection herewith.

          (b) On or before the twenty-fifth (25th) Trading Day prior to each
Fundamental Change Repurchase Date, the Company, or at its written request the
Trustee in the name of and at the expense of the Company (which request must be
received by the Trustee at least ten (10) Business Days prior to the date the
Trustee is requested to give notice as described below, unless the Trustee shall
agree to a shorter period), shall mail or cause to be mailed, by first class
mail, to all holders of record on such date a notice (the "FUNDAMENTAL CHANGE
REPURCHASE NOTICE") of the occurrence of such Fundamental Change and of the
repurchase right at the option of the holders arising as a result thereof to
each holder of Debentures at its last address as the same appears on the
Debenture Register; PROVIDED that if the Company shall give such notice, it
shall also give written notice of the Fundamental Change to the Trustee (and the
Paying Agent, if the Trustee is not then the Paying Agent) at such time as it is
mailed to Debentureholders; and FURTHER PROVIDED that, in any event, the notice
shall be prepared by the Company. Such notice, if mailed in the manner herein
provided, shall be conclusively presumed to have been duly given, whether or not
the holder receives such notice. Each Fundamental Change Repurchase Notice shall
state:

          (i)    the Fundamental Change Repurchase Price, excluding accrued and
     unpaid interest, the Conversion Rate at the time of such notice (and any
     applicable adjustments to such Conversion Rate) and, to the extent known at
     the time of such notice, the amount of interest (including Contingent
     Interest and Additional Interest, if any) that will be payable with respect
     to the Debentures on the Fundamental Change Repurchase Date;

          (ii)   the Make-Whole Premium, if any;

          (iii)  the events constituting the Fundamental Change and the date of
     the Fundamental Change;

          (iv)   the Fundamental Change Repurchase Date;

          (v)    the last date on which a holder may exercise the repurchase
     right;

          (vi)   the name and address of the Paying Agent and the Conversion
     Agent;

          (vii)  that Debentures as to which a Fundamental Change Repurchase
     Election has been given by the holder may be converted only if the election
     has been withdrawn by the holder in accordance with the terms of this
     Indenture; PROVIDED that the Debentures are otherwise convertible in
     accordance with Section 15.01;

                                       23
<Page>

          (viii) that the holder shall have the right to withdraw any Debentures
     surrendered prior to the close of business on the Business Day immediately
     preceding the Fundamental Change Repurchase Date (or any such later time as
     may be required by applicable law);

          (ix)   a description of the procedure which a Debentureholder must
     follow to exercise such repurchase right or to withdraw any surrendered
     Debentures;

          (x)    the CUSIP number or numbers of the Debentures (if then
     generally in use); and

          (xi)   briefly, the conversion rights of the Debentures and whether,
     at the time of such notice, the Debentures are eligible for conversion.

          No failure of the Company to give the foregoing notices and no defect
therein shall limit the Debentureholders' repurchase rights or affect the
validity of the proceedings for the repurchase of the Debentures pursuant to
this Section 3.05.

          (c) Debentures shall be repurchased pursuant to this Section 3.05 at
the option of the holder upon:

          (i)    delivery to the Trustee (or other Paying Agent appointed by the
     Company) by a holder of a duly completed notice (a "FUNDAMENTAL CHANGE
     REPURCHASE ELECTION") in the form set forth on the reverse of the Debenture
     at any time prior to the close of business on the Business Day immediately
     preceding the Fundamental Change Repurchase Date, subject to extension to
     comply with applicable law, stating:

                 (a)   if certificated Debentures have been issued, the
          certificate numbers of the Debentures which the holder shall deliver
          to be repurchased;

                 (b)   the portion of the principal amount of the Debentures
          that the holder shall deliver to be repurchased, which portion must be
          $1,000 or an integral multiple thereof; and

                 (c)   that such Debentures shall be repurchased as of the
          Fundamental Change Repurchase Date pursuant to the terms and
          conditions specified in the Debentures and in this Indenture; and

          (ii)   delivery or book-entry transfer of the Debentures to the
     Trustee (or other Paying Agent appointed by the Company) simultaneously
     with or at any time after delivery of the Fundamental Change Repurchase
     Election (together with all necessary endorsements) at the Corporate Trust
     Office of the Trustee (or other Paying Agent appointed by the Company) in
     the Borough of Manhattan, such delivery or transfer being a condition to
     receipt by the holder of the Fundamental Change Repurchase Price therefor;
     PROVIDED that such Fundamental Change Repurchase Price shall be so paid
     pursuant to this Section 3.05 only if the Debentures so delivered or
     transferred to the Trustee (or other Paying Agent appointed by the Company)
     shall conform in all respects

                                       24
<Page>

     to the description thereof in the related Fundamental Change Repurchase
     Election. All questions as to the validity, eligibility (including time of
     receipt) and acceptance of any Debenture for repurchase shall be determined
     by the Company, whose determination shall be final and binding absent
     manifest error.

     (d)  Without limiting the foregoing:

          (i)    If a Fundamental Change (other than a Fundamental Change
     relating solely to paragraph (b) of the definition thereof) occurs at any
     time prior to June 15, 2011, then the Fundamental Change Repurchase Price
     will include a make-whole-premium (a "MAKE-WHOLE-PREMIUM") calculated as
     provided below.

          (ii)   The Make-Whole Premium will equal the product of the original
     principal amount of the Debentures and a specified percentage (the
     "ADDITIONAL PREMIUM"). The Additional Premium will be determined by
     reference to the table set forth below and will be based on the date on
     which the Fundamental Change becomes effective (the "EFFECTIVE DATE") and
     the price (the "STOCK PRICE") paid per share of Common Stock in the
     transaction constituting the Fundamental Change. If holders of Common Stock
     receive only cash in the Fundamental Change, the Stock Price shall be the
     cash amount paid per share. If holders of Common Stock receive a
     combination of cash and other property in the Fundamental Change, the Stock
     Price shall be the average of the Last Reported Sale Price of the Common
     Stock on the five (5) Trading Days up to, but not including, the Effective
     Date of the Fundamental Change.

          The Stock Prices set forth in the first row of the table below will be
     adjusted as of any date on which the Conversion Rate of the Debentures is
     adjusted. The adjusted Stock Prices will equal the Stock Prices applicable
     immediately prior to such Adjustment Event, multiplied by a fraction, the
     numerator of which is the Conversion Rate immediately prior to the
     Adjustment Event giving rise to the Stock Price adjustment and the
     denominator of which is the Conversion Rate as so adjusted.

          The following table sets forth the Additional Premiums as percentages
     of the original principal amount of Debentures:

<Table>
<Caption>
  Effective
     Date                                                           Stock Price
------------- ----------------------------------------------------------------------------------------------------------------------
              $32.14  $38.00  $44.00 $50.00  $56.00  $62.00  $68.00  $74.00 $80.00  $86.00  $92.00  $98.00 $104.00  $110.00  $116.00
              ------  ------  ------ ------  ------  ------  ------  ------ ------  ------  ------  ------ -------  -------  -------
<S>             <C>    <C>     <C>    <C>     <C>     <C>     <C>     <C>    <C>     <C>     <C>     <C>     <C>      <C>       <C>
June 15, 2004   0.0%   14.3%   17.4%  15.9%   14.8%   13.9%   13.2%   12.6%  12.1%   11.6%   11.2%   10.9%   10.5%    10.2%     0.0%
June 15, 2005   0.0%   13.7%   16.5%  14.9%   13.6%   12.7%   12.0%   11.4%  10.9%   10.4%   10.1%    9.7%    9.4%     9.1%     0.0%
June 15, 2006   0.0%   12.9%   15.3%  13.5%   12.2%   11.2%   10.5%    9.9%   9.4%    9.0%    8.7%    8.4%    8.1%     7.9%     0.0%
June 15, 2007   0.0%   12.2%   14.2%  12.1%   10.6%    9.5%    8.8%    8.2%   7.8%    7.4%    7.1%    6.9%    6.6%     6.5%     0.0%
June 15, 2008   0.0%   10.9%   12.3%  10.0%    8.4%    7.4%    6.6%    6.1%   5.8%    5.5%    5.3%    5.1%    4.9%     4.8%     0.0%
June 15, 2009   0.0%    9.2%   10.0%   7.3%    5.7%    4.7%    4.1%    3.8%   3.5%    3.4%    3.2%    3.1%    3.1%     3.0%     0.0%
June 15, 2010   0.0%    6.4%    6.3%   3.5%    2.2%    1.6%    1.3%    1.2%   1.1%    1.1%    1.1%    1.0%    1.0%     1.0%     0.0%
June 15, 2011   0.0%    0.0%    0.0%   0.0%    0.0%    0.0%    0.0%    0.0%   0.0%    0.0%    0.0%    0.0%    0.0%     0.0%     0.0%
</Table>

          The exact Stock Price and repurchase dates may not be set forth in the
     table above, in which case:

                                       25
<Page>

                 (A)   If the Stock Price is between two Stock Price amounts
          shown on the table above or the Fundamental Change Repurchase Date is
          between two Effective Dates shown on the table above, the Additional
          Premium will be determined by a straight-line interpolation between
          the Additional Premium amounts set forth for the higher and lower
          Stock Price amounts and the two dates, as applicable, based on a
          365-day year.

                 (B)   If the Stock Price is equal to or in excess of $116.00
          per share of Common Stock (subject to adjustment), no Make-Whole
          premium will be paid.

                 (C)   If the Stock Price is less than or equal to $32.14 per
          share of Common Stock (subject to adjustment), no Make-Whole premium
          will be paid..

          (iii)  The Make-Whole Premium so calculated payable to a holder of
     Debentures who elects to require the Company to repurchase such Debentures
     pursuant to this Section 3.05 will be payable in cash, shares of Common
     Stock or a combination thereof at the Company's option.

          (iv)   Notice of any Make-Whole Premium shall be included in the
     Fundamental Change Repurchase Notice described in Section 3.05(b) above and
     such notice shall include the Make-Whole Premium amount and procedure for
     delivery by the Company of such Make-Whole Premium.

          SECTION 3.06.  REPURCHASE OF DEBENTURES BY THE COMPANY AT OPTION OF
HOLDERS ON SPECIFIED DATES. (a) On each of June 15, 2011, June 15, 2014, June
15, 2019, June 15, 2024 and June 15, 2029 (each, a "COMPANY REPURCHASE DATE"),
each holder shall have the right, at such holder's option, to require the
Company to repurchase for cash all of such holder's Debentures, or any portion
thereof that is a multiple of $1,000 principal amount. The Company shall
repurchase such Debentures at a price (the "COMPANY REPURCHASE PRICE") equal to
100% of the principal amount of the Debentures to be repurchased plus accrued
and unpaid interest (including Contingent Interest and Additional Interest, if
any), if any, to (but excluding) the Company Repurchase Date; PROVIDED that if
such Company Repurchase Date falls on an Interest Payment Date, then the
interest (including Contingent Interest and Additional Interest, if any) payable
on such Interest Payment Date shall be paid to the holders of record of the
Debentures on the applicable Regular Record Date instead of the holders
surrendering the Debentures for repurchase on such date.

          (b) On or before the twenty-fifth (25th) Trading Day prior to each
Company Repurchase Date, the Company, or at its written request the Trustee in
the name of and at the expense of the Company (which request must be received by
the Trustee at least ten (10) Business Days prior to the date the Trustee is
requested to give notice as described below, unless the Trustee shall agree to a
shorter period), shall mail or cause to be mailed, by first class mail, to the
Paying Agent and all holders of record on such date a notice (the "COMPANY
REPURCHASE NOTICE") to each holder of Debentures at its last address as the same
appears on the Debenture Register and to any beneficial owner of Debentures as
required by applicable law; PROVIDED that if the Company shall give such notice,
it shall also give written notice to the Trustee (and the Paying Agent if the
Trustee is not the Paying Agent) at such time as it is mailed to
Debentureholders; and FURTHER PROVIDED that, in any event, the notice shall be
prepared by the

                                       26
<Page>

Company. Such notice, if mailed in the manner herein provided, shall be
conclusively presumed to have been duly given, whether or not the holder
receives such notice. Each Company Repurchase Notice shall state:

          (i)    the Company Repurchase Price, excluding accrued and unpaid
     interest, the Conversion Rate at the time of such notice (and any
     applicable adjustments to the Conversion Rate) and, to the extent known at
     the time of such notice, the amount of interest (including Contingent
     Interest and Additional Interest, if any) that will be payable with respect
     to the Debentures on the Company Repurchase Date;

          (ii)   the Company Repurchase Date;

          (iii)  the last date on which a holder may exercise the repurchase
     right;

          (iv)   the name and address of the Paying Agent and the Conversion
     Agent;

          (v)    that Debentures as to which a Company Repurchase Election has
     been given by the holder may be converted only if the election has been
     withdrawn by the holder in accordance with the terms of this Indenture;
     PROVIDED that the Debentures are otherwise convertible in accordance with
     Section 15.01;

          (vi)   that the holder shall have the right to withdraw any Debentures
     surrendered prior to the close of business on the Business Day immediately
     preceding the Company Repurchase Date (or any such later time as may be
     required by applicable law);

          (vii)  a description of the procedure which a Debentureholder must
     follow to exercise such repurchase right or to withdraw any surrendered
     Debentures;

          (viii) the CUSIP number or numbers of the Debentures (if then
     generally in use); and

          (ix)   briefly, the conversion rights of the Debentures and whether,
     at the time of such notice, the Debentures are eligible for conversion.

          No failure of the Company to give the foregoing notices and no defect
therein shall limit the Debentureholders' repurchase rights or affect the
validity of the proceedings for the repurchase of the Debentures pursuant to
this Section 3.06.

          (c) Debentures shall be repurchased pursuant to this Section 3.06 at
the option of the holder upon:

          (i)    delivery to the Trustee (or other Paying Agent appointed by the
     Company) by a holder of a duly completed notice (a "COMPANY REPURCHASE
     ELECTION") in the form set forth on the reverse of the Debenture at any
     time from the opening of business on the twentieth (20th) Business Day
     preceding the Company Repurchase Date until the close of business on the
     Business Day immediately preceding the Company Repurchase Date, subject to
     extension to comply with applicable law, stating:

                                       27
<Page>

                 (1)   if certificated Debentures have been issued, the
          certificate numbers of the Debentures which the holder shall deliver
          to be repurchased;

                 (2)   the portion of the principal amount of the Debentures
          that the holder shall deliver to be repurchased, which portion must be
          $1,000 or an integral multiple thereof; and

                 (3)   that such Debentures shall be repurchased as of the
          Company Repurchase Date pursuant to the terms and conditions specified
          in the Debentures and in this Indenture; and

          (ii)   delivery or book entry transfer of the Debentures to the
     Trustee (or other Paying Agent appointed by the Company), simultaneously
     with or at any time after delivery of the Company Repurchase Election
     (together with all necessary endorsements) at the Corporate Trust Office of
     the Trustee (or other Paying Agent appointed by the Company) in the Borough
     of Manhattan, such delivery or transfer being a condition to receipt by the
     holder of the Company Repurchase Price therefor; PROVIDED that such Company
     Repurchase Price shall be so paid pursuant to this Section 3.06 only if the
     Debentures so delivered or transferred to the Trustee (or other Paying
     Agent appointed by the Company) shall conform in all respects to the
     description thereof in the related Company Repurchase Election. All
     questions as to the validity, eligibility (including time of receipt) and
     acceptance of any Debenture for repurchase shall be determined by the
     Company, whose determination shall be final and binding absent manifest
     error.

          If the Debentures are not in certificated form, holders must provide
notice of their election in accordance with the appropriate procedures of the
Depositary in a timely manner.

          SECTION 3.07.  RESERVED.

          SECTION 3.08.  CONDITIONS AND PROCEDURES FOR REPURCHASE AT OPTION OF
HOLDERS. (a) The Company may repurchase from the holder thereof, pursuant to
Section 3.05 or Section 3.06, a portion of a Debenture, if the principal amount
of such portion is $1,000 or a whole multiple of $1,000. Provisions of this
Indenture that apply to the repurchase of all of a Debenture also apply to the
repurchase of such portion of such Debenture. Upon presentation of any Debenture
repurchased in part only, the Company shall execute and the Trustee shall
authenticate and make available for delivery to the holder thereof, at the
expense of the Company, a new Debenture or Debentures, of any authorized
denomination, in aggregate principal amount equal to the portion of the
Debentures presented that is not repurchased.

          (b) On or prior to a Repurchase Date, the Company will deposit with
the Trustee or with one or more Paying Agents (or, if the Company or a Wholly
Owned Subsidiary is acting as Paying Agent, set aside, segregate and hold in
trust (or in the case of a Wholly Owned Subsidiary, the Company shall cause such
Wholly Owned Subsidiary to so set aside, segregate and hold) as provided in
Section 4.04) an amount of cash sufficient to repurchase on the Repurchase Date
all of the Debentures (or portions thereof) to be repurchased on such date at
the Repurchase Price; PROVIDED that if such deposit is made on the Repurchase
Date, it must be

                                       28
<Page>

received by the Trustee or Paying Agent, as the case may be, by 10:00 a.m., New
York City time, on such date.

          If the Trustee or other Paying Agent appointed by the Company, or the
Company or a Wholly Owned Subsidiary, if it, or a Wholly Owned Subsidiary is
acting as the Paying Agent, holds cash sufficient to pay the aggregate
Repurchase Price of all of the Debentures (or portions thereof) that are to be
repurchased as of the Repurchase Date, then on or after the Repurchase Date, (i)
such Debentures to be repurchased will cease to be outstanding, (ii) interest on
such Debentures to be repurchased will cease to accrue, whether or not book
entry transfer of the Debentures has been made or the Debentures have been
delivered to the Trustee or Paying Agent, and (iii) all other rights of the
holders of such Debentures to be repurchased will terminate other than the right
to receive the Repurchase Price upon transfer or delivery of the Debentures.

          (c) Upon receipt by the Trustee (or other Paying Agent appointed by
the Company) of a Repurchase Election, the holder of the Debenture in respect of
which such Repurchase Election was given shall (unless such notice is validly
withdrawn) thereafter be entitled to receive solely the Repurchase Price with
respect to such Debenture. Such Repurchase Price shall be paid to such holder,
subject to receipt of funds and/or Debentures by the Trustee (or other Paying
Agent appointed by the Company), promptly (but in no event more than five (5)
Business Days) following the later of (x) the Repurchase Date with respect to
such Debenture (PROVIDED that the holder has satisfied the conditions in Section
3.05(c) or Section 3.06(c), as applicable) and (y) the time of book-entry
transfer or delivery of such Debenture to the Trustee (or other Paying Agent
appointed by the Company) by the holder thereof in the manner required by
Section 3.05(c) or Section 3.06(c), as applicable. Debentures in respect of
which a Repurchase Election has been given by the holder thereof may not be
converted pursuant to Article 15 hereof on or after the date of the delivery of
such Repurchase Election unless such notice has first been validly withdrawn.

          (d) Notwithstanding anything herein to the contrary, any holder
delivering to the Trustee (or other Paying Agent appointed by the Company) a
Repurchase Election shall have the right to withdraw such election at any time
prior to the close of business on the Business Day immediately preceding the
Repurchase Date (or any such later time as may be required by applicable law) by
delivery of a written notice of withdrawal to the Trustee (or other Paying Agent
appointed by the Company) specifying:

          (i)    the certificate number, if any, of the Debentures in respect of
     which such notice of withdrawal is being submitted, or the appropriate
     Depositary information if the Debentures in respect of which such notice of
     withdrawal is being submitted is represented by a Global Debenture,

          (ii)   the principal amount of the Debentures with respect to which
     such notice of withdrawal is being submitted, and

          (iii)  the principal amount, if any, of such Debentures which remain
     subject to the original Repurchase Election and which has been or will be
     delivered for repurchase by the Company.

                                       29
<Page>

          The Trustee (or other Paying Agent appointed by the Company) shall
promptly notify the Company of the receipt by it of any Repurchase Election or
written notice of withdrawal thereof.

          (e) The Company will comply with the provisions of Rules 13e-4 and
14e-1 and any other tender offer rules under the Exchange Act to the extent then
applicable in connection with the repurchase rights of the holders of Debentures
in the event of a Fundamental Change Repurchase Date or on any Company
Repurchase Date. If then required by applicable law, the Company will file a
Schedule TO or any other schedule required in connection with such repurchase.

          (f) There shall be no repurchase of any Debentures pursuant to Section
3.05 or Section 3.06 if there has occurred at any time prior to, and is
continuing on, the Repurchase Date an Event of Default (other than an Event of
Default that is cured by the payment of the Repurchase Price with respect to
such Debentures). The Paying Agent will promptly return to the respective
holders thereof any Debentures (x) with respect to which a Repurchase Election
has been withdrawn in compliance with this Indenture or (y) held by it during
the continuance of an Event of Default (other than a default in the payment of
the Repurchase Price with respect to such Debentures) in which case, upon such
return, the Repurchase Election with respect thereto shall be deemed to have
been withdrawn.

          (g) The Trustee (or other Paying Agent appointed by the Company) shall
return to the Company any cash that remains unclaimed as provided in Section
12.03, for the payment of the Repurchase Price; PROVIDED that, to the extent
that the aggregate amount of cash deposited by the Company pursuant to Section
3.08(b) exceeds the aggregate Repurchase Price of the Debentures or portions
thereof which the Company is obligated to purchase as of the Repurchase Date,
then, unless otherwise agreed in writing with the Company, promptly after the
Business Day following the Repurchase Date, the Trustee shall return any such
excess to the Company.

          (h) In the case of a reclassification, change, consolidation, merger,
combination, sale or conveyance to which Section 15.06 applies, in which the
Common Stock of the Company is changed or exchanged as a result into the right
to receive stock, securities or other property or assets (including cash), which
includes shares of Common Stock of the Company or shares of common stock of
another Person that are, or upon issuance will be, traded on a United States
national securities exchange or approved for trading on an established automated
over-the-counter trading market in the United States and such shares constitute
at the time such change or exchange becomes effective in excess of 50% of the
aggregate fair market value of such stock, securities or other property or
assets (including cash) (as determined by the Company, which determination shall
be conclusive and binding), then the Person formed by such consolidation or
resulting from such merger or which acquires such assets, as the case may be,
shall execute and deliver to the Trustee a supplemental indenture (accompanied
by an Opinion of Counsel that such supplemental indenture complies with the
Trust Indenture Act as in force at the date of execution of such supplemental
indenture and complies with the terms hereof) modifying the provisions of this
Indenture relating to the right of holders of the Debentures to cause the
Company to repurchase the Debentures following a Fundamental Change and the
provisions of this Indenture relating to the Company's option to deliver shares
of Common Stock in payment of the Repurchase Price, including, without
limitation, the applicable provisions of this Article 3

                                       30
<Page>

and the definitions of Common Stock and Fundamental Change, as appropriate, as
determined in good faith by the Company (which determination shall be conclusive
and binding), to make such provisions correspondingly apply to such other Person
if different from the Company and the common stock issued by such Person (in
lieu of the Company and the Common Stock of the Company).

                                    ARTICLE 4
                       PARTICULAR COVENANTS OF THE COMPANY

          SECTION 4.01.  PAYMENT OF PRINCIPAL AND INTEREST. The Company
covenants and agrees that it will duly and punctually pay or cause to be paid
the principal of (including any Redemption Price or Repurchase Price pursuant to
Article 3) and interest (including Contingent Interest and Additional Interest,
if any) on each of the Debentures at the places, at the respective times and in
the manner provided herein and in the Debentures. The Company shall pay interest
(including Contingent Interest and Additional Interest, if any) on overdue
principal at the rate specified in the Debentures, and shall pay interest on
overdue installments of interest at the same rate to the extent lawful.

          SECTION 4.02.  MAINTENANCE OF OFFICE OR AGENCY. The Company will
maintain an office or agency in the Borough of Manhattan, The City of New York,
where the Debentures may be surrendered for registration of transfer or exchange
or presented for payment or for conversion, redemption or repurchase and where
notices and demands to or upon the Company in respect of the Debentures and this
Indenture may be served. The Company will give prompt written notice to the
Trustee of the location, and any change in the location, of such office or
agency not designated or appointed by the Trustee. If at any time the Company
shall fail to maintain any such required office or agency or shall fail to
furnish the Trustee with the address thereof, such presentations, surrenders,
notices and demands may be made or served at the Corporate Trust Office.

          The Company may also from time to time designate co debenture
registrars and one or more offices or agencies where the Debentures may be
presented or surrendered for any or all such purposes and may from time to time
rescind such designations. The Company will give prompt written notice to the
Trustee of any such designation or rescission and of any change in the location
of any such other office or agency.

          The Company hereby initially designates the Trustee as Paying Agent,
Debenture Registrar, Custodian and Conversion Agent, and each of the Corporate
Trust Office and the office or agency of the Trustee in the Borough of Manhattan
shall be considered as one such office or agency of the Company for each of the
aforesaid purposes.

          So long as the Trustee is the Debenture Registrar, the Trustee agrees
to mail, or cause to be mailed, the notices set forth in Section 7.07(a) and in
Section 7.07(c). If co-debenture registrars have been appointed in accordance
with this Section and Article 2, the Trustee shall mail such notices only to the
Company and the holders of Debentures it can identify from its records.

                                       31
<Page>

          SECTION 4.03.  APPOINTMENTS TO FILL VACANCIES IN TRUSTEE'S OFFICE. The
Company, whenever necessary to avoid or fill a vacancy in the office of Trustee,
will appoint, in the manner provided in Section 7.07(b), a Trustee, so that
there shall at all times be a Trustee hereunder.

          SECTION 4.04.  PROVISIONS AS TO PAYING AGENT. (a) If the Company shall
appoint a Paying Agent other than the Trustee, the Company will cause such
Paying Agent to execute and deliver to the Trustee an instrument in which such
Paying Agent shall agree with the Trustee, subject to the provisions of this
Section 4.04:

          (i)    that it will hold all sums held by it as such agent for the
     payment of the principal of or interest (including Contingent Interest and
     Additional Interest, if any) on the Debentures (whether such sums have been
     paid to it by the Company or by any other obligor on the Debentures, or
     otherwise) in trust for the benefit of the holders of the Debentures;

          (ii)   that it will give the Trustee notice of any failure by the
     Company (or by any other obligor on the Debentures) to make any payment of
     the principal of or interest (including Contingent Interest and Additional
     Interest, if any) on the Debentures when the same shall be due and payable;
     and

          (iii)  that at any time during the continuance of an Event of Default,
     upon request of the Trustee, it will forthwith pay to the Trustee all sums
     so held in trust.

          The Company shall, on or before each due date of the principal of or
interest (including Contingent Interest and Additional Interest, if any) on the
Debentures, deposit with the Paying Agent a sum (in funds which are immediately
available on the due date for such payment) sufficient to pay such principal or
interest (including Contingent Interest and Additional Interest, if any), and
(unless such Paying Agent is the Trustee) the Company will promptly notify the
Trustee of any failure to take such action; PROVIDED that if such deposit is
made on the due date, such deposit shall be received by the Paying Agent by
10:00 a.m., New York City time, on such date.

          (b) If the Company or a Wholly Owned Subsidiary shall act as Paying
Agent, the Company will (or will cause such Wholly Owned Subsidiary to), on or
before each due date of the principal of or interest (including Contingent
Interest and Additional Interest, if any) on the Debentures, set aside,
segregate and hold in trust for the benefit of the holders of the Debentures a
sum sufficient to pay such principal or interest (including Contingent Interest
and Additional Interest, if any) so becoming due and will promptly notify the
Trustee of any failure to take such action and of any failure by the Company (or
any other obligor under the Debentures) to make any payment of the principal of
or interest (including Contingent Interest and Additional Interest, if any) on
the Debentures when the same shall become due and payable.

          (c) Anything in this Section 4.04 to the contrary notwithstanding, the
Company may, at any time, for the purpose of obtaining a satisfaction and
discharge of this Indenture, or for any other reason, pay or cause to be paid to
the Trustee all sums held in trust by the Company, such Wholly Owned Subsidiary
or such Paying Agent hereunder as required by this

                                       32
<Page>

Section 4.04, such sums to be held by the Trustee upon the trusts herein
contained and upon such payment by the Company, such Wholly Owned Subsidiary or
such Paying Agent to the Trustee, the Company, such Wholly Owned Subsidiary or
such Paying Agent shall be released from all further liability with respect to
such sums.

          (d) Anything in this Section 4.04 to the contrary notwithstanding, the
agreement to hold sums in trust as provided in this Section 4.04 is subject to
Sections 12.02 and 12.03.

          The Trustee shall not be responsible for the actions of any other
Paying Agents (including the Company or a Wholly Owned Subsidiary if acting as
Paying Agent) and shall have no control of any funds held by such other Paying
Agents.

          SECTION 4.05.  EXISTENCE. Subject to Article 11, the Company will do
or cause to be done all things necessary to preserve and keep in full force and
effect its existence and rights (both organizational and statutory); PROVIDED
that the Company shall not be required to preserve any such right if the Company
shall determine that the preservation thereof is no longer desirable in the
conduct of the business of the Company and that the loss thereof is not
disadvantageous in any material respect to the Debentureholders.

          SECTION 4.06.  RULE 144A INFORMATION REQUIREMENT. Within the period
prior to the expiration of the holding period applicable to sales thereof under
Rule 144(k) under the Securities Act (or any successor provision), the Company
covenants and agrees that it shall, during any period in which it is not subject
to Section 13 or 15(d) under the Exchange Act, make available to any holder or
beneficial holder of Debentures or any Common Stock issued upon conversion or
repurchase thereof which continue to be Restricted Securities in connection with
any sale thereof, and any prospective purchaser of such Debentures or such
Common Stock designated by such holder or beneficial holder, the information
required pursuant to Rule 144A(d)(4) under the Securities Act upon the request
of any holder or beneficial holder of such Debentures or such Common Stock and
it will take such further action as any holder or beneficial holder of such
Debentures or such Common Stock may reasonably request, all to the extent
required from time to time to enable such holder or beneficial holder to sell
such Debentures or such Common Stock without registration under the Securities
Act within the limitation of the exemption provided by Rule 144A, as such Rule
may be amended from time to time. Upon the request of any holder or any
beneficial holder of such Debentures or such Common Stock, the Company will
deliver to such holder or beneficial holder a written statement as to whether it
has complied with such requirements.

          SECTION 4.07.  STAY, EXTENSION AND USURY LAWS. The Company covenants
(to the extent that it may lawfully do so) that it shall not at any time insist
upon, plead, or in any manner whatsoever claim or take the benefit or advantage
of, any stay, extension or usury law or other law which would prohibit or
forgive the Company from paying all or any portion of the principal of or
interest on the Debentures as contemplated herein, wherever enacted, now or at
any time hereafter in force, or which may affect the covenants or the
performance of this Indenture and the Company (to the extent it may lawfully do
so) hereby expressly waives all benefit or advantage of any such law, and
covenants that it will not, by resort to any such law, hinder, delay or impede
the execution of any power herein granted to the Trustee, but will suffer and
permit the execution of every such power as though no such law had been enacted.

                                       33
<Page>

          SECTION 4.08.  COMPLIANCE CERTIFICATE. The Company shall deliver to
the Trustee, within one hundred twenty (120) days after the end of each fiscal
year of the Company (which fiscal year of the Company is presently the fifty-two
(52) or fifty-three (53), as the case may be, weeks ending on the last Saturday
of each November), a certificate signed by either the principal executive
officer, principal financial officer or principal accounting officer of the
Company, stating whether or not to the best knowledge of the signer thereof the
Company is in default in the performance and observance of any of the terms,
provisions and conditions of this Indenture (without regard to any period of
grace or requirement of notice provided hereunder) and, if the Company shall be
in default, specifying all such defaults and the nature and the status thereof
of which the signer may have knowledge.

          The Company will deliver to the Trustee, promptly upon becoming aware
of (i) any default in the performance or observance of any covenant, agreement
or condition contained in this Indenture or (ii) any Event of Default, an
Officers' Certificate specifying with particularity such default or Event of
Default and further stating what action the Company has taken, is taking or
proposes to take with respect thereto.

          Any notice required to be given under this Section 4.08 shall be
delivered to a Trust Officer of the Trustee at its Corporate Trust Office.

          SECTION 4.09.  ADDITIONAL INTEREST NOTICE. (a) In the event that the
Company is required to pay Additional Interest to holders of Debentures pursuant
to the Registration Rights Agreement, the Company will provide written notice
("ADDITIONAL INTEREST NOTICE") to the Trustee of its obligation to pay
Additional Interest no later than fifteen (15) days prior to the proposed
payment date for the Additional Interest, and the Additional Interest Notice
shall set forth the amount of Additional Interest to be paid by the Company on
such payment date. The Trustee shall not at any time be under any duty or
responsibility to any holder of Debentures to determine the Additional Interest,
or with respect to the nature, extent or calculation of the amount of Additional
Interest when made, or with respect to the method employed in such calculation
of the Additional Interest.

          SECTION 4.10.  CONTINGENT DEBT TAX TREATMENT. The Company agrees, and
by acceptance of a beneficial ownership interest in the Debentures each holder
and each beneficial owner of the Debentures will be deemed to have agreed, for
United States federal income tax purposes (a) to treat the Debentures as
indebtedness of the Company that is subject to Treasury regulations section
1.1275-4 (the "CONTINGENT DEBT REGULATIONS") and, for purposes of the Contingent
Debt Regulations, to treat the fair market value of any Common Stock
beneficially received upon any conversion of the Debentures as a contingent
payment, (b) to accrue interest with respect to the Debentures as original issue
discount on a constant yield to maturity basis using the comparable yield of
7.0% per annum compounded semi-annually and (c) to be bound by the "comparable
yield" and the "projected payment schedule" within the meaning of the Contingent
Debt Regulations, as determined by the Company. A holder or beneficial owner may
obtain the issue price, amount of original issue discount, issue date, yield to
maturity, comparable yield and projected payment schedule for the Debentures by
submitting a written request for such information to the Company at the
following address: Charles River Associates Incorporated, 200 Clarendon Street,
T-33, Boston, Massachusetts 02116, Attention: Chief Financial Officer.

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                                    ARTICLE 5
       DEBENTUREHOLDERS' LISTS AND REPORTS BY THE COMPANY AND THE TRUSTEE

          SECTION 5.01.  DEBENTUREHOLDERS' LISTS. The Company covenants and
agrees that it will furnish or cause to be furnished to the Trustee,
semiannually, not more than fifteen (15) days after each June 1 and December 1
in each year beginning with December 1, 2004, and at such other times as the
Trustee may request in writing, within thirty (30) days after receipt by the
Company of any such request (or such lesser time as the Trustee may reasonably
request in order to enable it to timely provide any notice to be provided by it
hereunder), a list in such form as the Trustee may reasonably require of the
names and addresses of the holders of Debentures as of a date not more than
fifteen (15) days (or such other date as the Trustee may reasonably request in
order to so provide any such notices) prior to the time such information is
furnished, except that no such list need be furnished by the Company to the
Trustee so long as the Trustee is acting as the sole Debenture Registrar.

          SECTION 5.02.  PRESERVATION AND DISCLOSURE OF LISTS. (a) The Trustee
shall preserve, in as current a form as is reasonably practicable, all
information as to the names and addresses of the holders of Debentures contained
in the most recent list furnished to it as provided in Section 5.01 or
maintained by the Trustee in its capacity as Debenture Registrar or co-debenture
registrar in respect of the Debentures, if so acting. The Trustee may destroy
any list furnished to it as provided in Section 5.01 upon receipt of a new list
so furnished.

          (b) The rights of Debentureholders to communicate with other holders
of Debentures with respect to their rights under this Indenture or under the
Debentures, and the corresponding rights and duties of the Trustee, shall be as
provided by the Trust Indenture Act. The Company, the Trustee and the Debenture
Registrar shall have the protection of Section 312(c) of the Trust Indenture
Act.

          (c) Every Debentureholder, by receiving and holding the same, agrees
with the Company and the Trustee that neither the Company nor the Trustee nor
any agent of either of them shall be held accountable by reason of any
disclosure of information as to names and addresses of holders of Debentures
made pursuant to the Trust Indenture Act.

          SECTION 5.03.  REPORTS BY TRUSTEE. (a) Within sixty (60) days after
June 15 of each year commencing with the year 2005, the Trustee shall transmit
to holders of Debentures such reports dated as of June 15 of the year in which
such reports are made concerning the Trustee and its actions under this
Indenture as may be required pursuant to the Trust Indenture Act at the times
and in the manner provided pursuant thereto. In the event that no events have
occurred under the applicable sections of the Trust Indenture Act, the Trustee
shall be under no duty or obligation to provide such reports.

          (b) A copy of such report shall, at the time of such transmission to
holders of Debentures, be filed by the Trustee with each stock exchange and
automated quotation system upon which the Debentures are listed and with the
Company. The Company will promptly notify the Trustee in writing when the
Debentures are listed on any stock exchange or automated quotation system or
delisted therefrom.

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<Page>

          SECTION 5.04.  REPORTS BY THE COMPANY. The Company shall file with the
Trustee (and the Commission at any time after this Indenture becomes qualified
under the Trust Indenture Act), and transmit to holders of Debentures, such
information, documents and other reports and such summaries thereof, as may be
required pursuant to the Trust Indenture Act at the times and in the manner
provided pursuant to such Act, whether or not the Debentures are governed by
such Act; PROVIDED that any such information, document or report required to be
filed with the Commission pursuant to Section 13 or 15(d) of the Exchange Act
shall be filed with the Trustee within fifteen (15) days after the same is so
required to be filed with the Commission. Delivery of such reports, information
and documents to the Trustee is for informational purposes only and the
Trustee's receipt of such shall not constitute constructive notice of any
information contained therein or determinable from information contained
therein, including the Company's compliance with any of its covenants hereunder
(as to which the Trustee is entitled to rely exclusively on an Officers'
Certificate).

                                    ARTICLE 6
       REMEDIES OF THE TRUSTEE AND DEBENTUREHOLDERS ON AN EVENT OF DEFAULT

          SECTION 6.01.  EVENTS OF DEFAULT. In case one or more of the following
events (each, an "EVENT OF DEFAULT") (whatever the reason for such Event of
Default and whether it shall be voluntary or involuntary or be effected by
operation of law or pursuant to any judgment, decree or order of any court or
any order, rule or regulation of any administrative or governmental body) shall
have occurred and be continuing:

          (a) default in the payment of any installment of interest (including
Contingent Interest and Additional Interest, if any) upon any of the Debentures,
as and when the same shall become due and payable, and continuance of such
default for a period of thirty (30) days;

          (b) default in the payment of the principal of any of the Debentures,
as and when the same shall become due and payable either at Stated Maturity or
in connection with any redemption or repurchase, in each case pursuant to
Article 3, by acceleration or otherwise;

          (c) default in the Company's obligation to deliver shares of Common
Stock, cash or other property upon conversion of any of the Debentures upon the
exercise of a holder's rights pursuant to Article 15 and continuance of such
default for ten (10) days or more;

          (d) default in the Company's obligation to repurchase the Debentures
at the option of a holder in connection with a Fundamental Change pursuant to
Section 3.05 or on specified dates pursuant to Section 3.06;

          (e) failure on the part of the Company to provide notice of the
occurrence of a Fundamental Change within 25 days after the occurrence of such
Fundamental Change as required by Section 3.05;

          (f) failure on the part of the Company to comply with the provisions
of Article 11;

          (g) default in the Company's obligation to redeem any of the
Debentures after it has exercised its option to redeem such Debentures;

                                       36
<Page>

          (h) failure on the part of the Company duly to comply with or observe
any other of the covenants, warranties or agreements on the part of the Company
in the Debentures or this Indenture (other than a covenant, warrant or agreement
a default in whose performance or whose breach is elsewhere in this Section 6.01
specifically dealt with) and continuance of such failure for a period of sixty
(60) days after the date on which written notice of such failure, requiring the
Company to remedy the same, shall have been given to the Company by the Trustee
or to the Company by the holders of at least 25% in aggregate principal amount
of the Debentures at the time outstanding determined in accordance with Section
8.04;

          (i) failure by the Company or any Subsidiary to pay any Indebtedness
after final maturity or the acceleration of any such Indebtedness by the holders
thereof because of a default and the total amount of such Indebtedness unpaid or
accelerated exceeds $10.0 million, or its foreign currency equivalent at the
time, and such failure to pay is not cured or the acceleration is not rescinded
or annulled within ten (10) days after written notice as provided herein;

          (j) the entering of any judgment or decree for the payment of money in
excess of $10.0 million, or its foreign currency equivalent at the time, above
the coverage under the applicable insurance policies and indemnities as to which
the relevant insurer or indemnitee has not disclaimed responsibility, against
the Company or any Subsidiary, which remains outstanding for a period of sixty
(60) days following the entry of such judgment or decree and is not discharged
or waived or does not have the execution thereof effectively stayed (including
by agreement) within ten (10) days after written notice to the Company from the
Trustee or the holders of at least 25% in aggregate principal amount of the
Debentures at the time outstanding determined in accordance with Section 8.04;

          (k) the Company or any of its Subsidiaries shall commence a voluntary
case or other proceeding seeking liquidation, reorganization or other relief
with respect to the Company or any Subsidiary or their debts under any
bankruptcy, insolvency or other similar law now or hereafter in effect or
seeking the appointment of a trustee, receiver, liquidator, custodian or other
similar official of the Company or any Subsidiary or any substantial part of the
property of the Company or any Subsidiary, or shall consent to any such relief
or to the appointment of or taking possession by any such official in an
involuntary case or other proceeding commenced against the Company or any
Subsidiary, or shall make a general assignment for the benefit of creditors, or
shall fail generally to pay their debts as they become due;

          (l) an involuntary case or other proceeding shall be commenced against
the Company or any Subsidiary seeking liquidation, reorganization or other
relief with respect to the Company or any Subsidiary or their debts under any
bankruptcy, insolvency or other similar law now or hereafter in effect or
seeking the appointment of a trustee, receiver, liquidator, custodian or other
similar official of the Company or any Subsidiary or any substantial part of the
property of the Company or any Subsidiary, and such involuntary case or other
proceeding remains undismissed or unstayed and in effect for a period of sixty
(60) consecutive days;

then, and in each and every such case (other than an Event of Default specified
in Section 6.01(k) or 6.01(l)), unless the principal of all of the Debentures
shall have already become due and payable, either the Trustee or the holders of
not less than 25% in aggregate principal amount of the Debentures then
outstanding determined in accordance with Section 8.04, by notice in

                                       37
<Page>

writing to the Company (and to the Trustee if given by Debentureholders), may
declare the principal of all the Debentures and the interest accrued thereon
(including Contingent Interest and Additional Interest, if any) to be due and
payable immediately, and upon any such declaration the same shall become and
shall be immediately due and payable, anything in this Indenture or in the
Debentures contained to the contrary notwithstanding. If an Event of Default
specified in Section 6.01(k) or 6.01(l) occurs, the principal of all the
Debentures and the interest accrued thereon (including Contingent Interest and
Additional Interest, if any) shall be immediately and automatically due and
payable without necessity of further action. This provision, however, is subject
to the conditions that if, at any time after the principal of the Debentures
shall have been so declared due and payable, and before any judgment or decree
for the payment of the monies due shall have been obtained or entered as
hereinafter provided, the Company shall pay or shall deposit with the Trustee a
sum sufficient to pay all matured installments of interest (including Contingent
Interest and Additional Interest, if any) upon all Debentures and the principal
of any and all Debentures which shall have become due otherwise than by
acceleration (with interest on overdue installments of interest (to the extent
that payment of such interest is enforceable under applicable law) and on such
principal at the rate borne by the Debentures, to the date of such payment or
deposit) and amounts due to the Trustee pursuant to Section 7.06, and if any and
all defaults under this Indenture, other than the nonpayment of principal of and
accrued and unpaid interest (including Contingent Interest and Additional
Interest, if any) on Debentures which shall have become due by acceleration,
shall have been cured or waived pursuant to Section 6.07, then and in every such
case the holders of a majority in aggregate principal amount of the Debentures
then outstanding determined in accordance with Section 8.04, by written notice
to the Company and to the Trustee, may waive all defaults or Events of Default
and rescind and annul such declaration and its consequences; but no such waiver
or rescission and annulment shall extend to or shall affect any subsequent
default or Event of Default, or shall impair any right consequent thereon. The
Company shall notify in writing a Trust Officer of the Trustee, promptly upon
becoming aware thereof, of any Event of Default as set forth in the second
paragraph of Section 4.08.

          In case the Trustee shall have proceeded to enforce any right under
this Indenture and such proceedings shall have been discontinued or abandoned
because of such waiver or rescission and annulment or for any other reason or
shall have been determined adversely to the Trustee, then and in every such case
the Company, the holders of Debentures, and the Trustee shall be restored
respectively to their several positions and rights hereunder, and all rights,
remedies and powers of the Company, the holders of Debentures, and the Trustee
shall continue as though no such proceeding had been taken.

          SECTION 6.02.  PAYMENTS OF DEBENTURES ON DEFAULT; SUIT THEREFOR. The
Company covenants that (a) in case default shall be made in the payment of any
installment of interest (including Contingent Interest and Additional Interest,
if any) upon any of the Debentures as and when the same shall become due and
payable, and such default shall have continued for a period of thirty (30) days,
or (b) in case default shall be made in the payment of the principal of any of
the Debentures as and when the same shall have become due and payable, whether
at maturity of the Debentures or in connection with any redemption, repurchase,
acceleration, declaration or otherwise, then, upon demand of the Trustee, the
Company will pay to the Trustee, for the benefit of the holders of the
Debentures, the whole amount that then shall have become due and payable on all
such Debentures for principal or interest (including

                                       38
<Page>

Contingent Interest and Additional Interest, if any), as the case may be, with
interest upon the overdue principal and interest (to the extent that payment of
such interest is enforceable under applicable law) upon the overdue installments
of interest at the rate borne by the Debentures, and, in addition thereto, such
further amount as shall be sufficient to cover the costs and expenses of
collection, including reasonable compensation to the Trustee, its agents,
attorneys and counsel, and all other amounts due the Trustee under Section 7.06.
Until such demand by the Trustee, the Company may pay the principal of and
interest (including Contingent Interest and Additional Interest, if any), on the
Debentures to the holders, whether or not the Debentures are overdue.

          In case the Company shall fail forthwith to pay such amounts upon such
demand, the Trustee, in its own name and as trustee of an express trust, shall
be entitled and empowered to institute any actions or proceedings at law or in
equity for the collection of the sums so due and unpaid, and may prosecute any
such action or proceeding to judgment or final decree, and may enforce any such
judgment or final decree against the Company or any other obligor on the
Debentures and collect in the manner provided by law out of the property of the
Company or any other obligor on the Debentures wherever situated the monies
adjudged or decreed to be payable.

          In case there shall be pending proceedings for the bankruptcy or for
the reorganization of the Company or any other obligor on the Debentures under
Title 11 of the United States Code, or any other applicable law, or in case a
receiver, assignee or trustee in bankruptcy or reorganization, liquidator,
sequestrator or similar official shall have been appointed for or taken
possession of the Company or such other obligor, the property of the Company or
such other obligor, or in the case of any other judicial proceedings relative to
the Company or such other obligor, or to the creditors or property of the
Company or such other obligor, the Trustee, irrespective of whether the
principal of the Debentures shall then be due and payable as therein expressed
or by declaration, acceleration or otherwise and irrespective of whether the
Trustee shall have made any demand pursuant to the provisions of this Section
6.02, shall be entitled and empowered, by intervention in such proceedings or
otherwise, to file and prove a claim or claims for the whole amount of principal
and interest (including Contingent Interest and Additional Interest, if any)
owing and unpaid in respect of the Debentures, and, in case of any judicial
proceedings, to file such proofs of claim and other papers or documents as may
be necessary or advisable in order to have the claims of the Trustee and of the
Debentureholders allowed in such judicial proceedings relative to the Company or
any other obligor on the Debentures, its or their creditors, or its or their
property, and to collect and receive any monies or other property payable or
deliverable on any such claims, and to distribute the same after the deduction
of any amounts due the Trustee under Section 7.06, and to take any other action
with respect to such claims, including participating as a member of any official
committee of creditors, as it reasonably deems necessary or advisable, and,
unless prohibited by law or applicable regulations, any receiver, assignee or
trustee in bankruptcy or reorganization, liquidator, custodian or similar
official is hereby authorized by each of the Debentureholders to make such
payments to the Trustee, and, in the event that the Trustee shall consent to the
making of such payments directly to the Debentureholders, to pay to the Trustee
any amount due it for reasonable compensation, expenses, advances and
disbursements, including counsel fees and expenses incurred by it up to the date
of such distribution. To the extent that such payment of reasonable
compensation, expenses, advances and disbursements out of the estate in any such
proceedings shall be denied for any reason, payment of the same shall be secured
by a Lien on,

                                       39
<Page>

and shall be paid out of, any and all distributions, dividends, monies,
securities and other property which the holders of the Debentures may be
entitled to receive in such proceedings, whether in liquidation or under any
plan of reorganization or arrangement or otherwise.

          All rights of action and of asserting claims under this Indenture, or
under any of the Debentures, may be enforced by the Trustee without the
possession of any of the Debentures, or the production thereof at any trial or
other proceeding relative thereto, and any such suit or proceeding instituted by
the Trustee shall be brought in its own name as trustee of an express trust, and
any recovery of judgment shall, after provision for the payment of the
reasonable compensation, expenses, disbursements and advances of the Trustee,
its agents and counsel, be for the ratable benefit of the holders of the
Debentures.

          In any proceedings brought by the Trustee (and in any proceedings
involving the interpretation of any provision of this Indenture to which the
Trustee shall be a party), the Trustee shall be held to represent all the
holders of the Debentures, and it shall not be necessary to make any holders of
the Debentures parties to any such proceedings.

          SECTION 6.03.  APPLICATION OF MONIES COLLECTED BY TRUSTEE. Any monies
collected by the Trustee pursuant to this Article 6 shall be applied in the
order following, at the date or dates fixed by the Trustee for the distribution
of such monies, upon presentation of the several Debentures, and stamping
thereon the payment, if only partially paid, and upon surrender thereof, if
fully paid:

                 FIRST: To the payment of all amounts due the Trustee under
     Section 7.06;

                 SECOND: In case the principal of the outstanding Debentures
     shall not have become due and be unpaid, to the payment of interest
     (including Contingent Interest and Additional Interest, if any) on the
     Debentures in default in the order of the maturity of the installments of
     such interest, with interest (to the extent that such interest has been
     collected by the Trustee) upon the overdue installments of interest at the
     rate borne by the Debentures, such payments to be made ratably to the
     Persons entitled thereto;

                 THIRD: In case the principal of the outstanding Debentures
     shall have become due, by acceleration, declaration or otherwise, and be
     unpaid, to the payment of the whole amount then owing and unpaid upon the
     Debentures for principal and interest (including Contingent Interest and
     Additional Interest, if any), with interest on the overdue principal and
     interest (to the extent that such interest has been collected by the
     Trustee) upon overdue installments of interest at the rate borne by the
     Debentures, and in case such monies shall be insufficient to pay in full
     the whole amounts so due and unpaid, then to the payment of such principal
     and interest without preference or priority of principal over interest, or
     of interest over principal, or of any installment of interest over any
     other installment of interest or of any Debenture over any other Debenture,
     ratably to the aggregate of such principal and interest; and

                 FOURTH: To the payment of the remainder, if any, to the Company
     or as a court of competent jurisdiction shall direct in writing.

                                       40
<Page>

          SECTION 6.04.  PROCEEDINGS BY DEBENTUREHOLDER. No holder of any
Debenture shall have any right by virtue of or by reference to any provision of
this Indenture to institute any suit, action or proceeding in equity or at law
upon or under or with respect to this Indenture, or for the appointment of a
receiver, trustee, liquidator, custodian or other similar official, or for any
other remedy hereunder, except for default in the payment of principal or
interest (including Contingent Interest and Additional Interest, if any), unless
such holder previously shall have given to the Trustee written notice of an
Event of Default and of the continuance thereof, as hereinbefore provided, and
unless also the holders of not less than 25% in aggregate principal amount of
the Debentures then outstanding determined in accordance with Section 8.04 shall
have made written request upon the Trustee to institute such action, suit or
proceeding in its own name as Trustee hereunder and shall have offered to the
Trustee such reasonable security or indemnity satisfactory to the Trustee as it
may require against the costs, expenses and liabilities of the Trustee to be
incurred therein or thereby, and the Trustee for sixty (60) days after its
receipt of such notice, request and offer of reasonable indemnity, shall have
neglected or refused to institute any such action, suit or proceeding and no
direction inconsistent with such written request shall have been given to the
Trustee pursuant to Section 6.07 within sixty (60) days of such notice; it being
understood and intended, and being expressly covenanted by the taker and holder
of every Debenture with every other taker and holder and the Trustee, that no
one or more holders of Debentures shall have any right in any manner whatever by
virtue of or by reference to any provision of this Indenture to affect, disturb
or prejudice the rights of any other holder of Debentures, or to obtain or seek
to obtain priority over or preference to any other such holder, or to enforce
any right under this Indenture, except in the manner herein provided and for the
equal, ratable and common benefit of all holders of Debentures (except as
otherwise provided herein). For the protection and enforcement of this Section
6.04, each and every Debentureholder and the Trustee shall be entitled to such
relief as can be given either at law or in equity.

          Notwithstanding any other provision of this Indenture and any
provision of any Debenture, the right of any holder of any Debenture to receive
payment of the principal of (including any Redemption Price or Repurchase Price
pursuant to Article 3 for) and accrued and unpaid interest (including Contingent
Interest and Additional Interest, if any) on such Debenture on or after the
respective due dates expressed in such Debenture, or to institute suit for the
enforcement of any such payment on or after such respective dates against the
Company, shall not be impaired or affected without the consent of such holder.

          Anything in this Indenture or the Debentures to the contrary
notwithstanding, the holder of any Debenture, without the consent of either the
Trustee or the holder of any other Debenture, on its own behalf and for its own
benefit, may enforce, and may institute and maintain any proceeding suitable to
enforce, its rights of conversion as provided herein.

          SECTION 6.05.  PROCEEDINGS BY TRUSTEE. In case of an Event of Default,
the Trustee may, in its discretion, proceed to protect and enforce the rights
vested in it by this Indenture by such appropriate judicial proceedings as are
necessary to protect and enforce any of such rights, either by suit in equity or
by action at law or by proceeding in bankruptcy or otherwise, whether for the
specific enforcement of any covenant or agreement contained in this Indenture or
in aid of the exercise of any power granted in this Indenture, or to enforce any
other legal or equitable right vested in the Trustee by this Indenture or by
law.

                                       41
<Page>

          SECTION 6.06.  REMEDIES CUMULATIVE AND CONTINUING. Except as provided
in Section 2.08, all powers and remedies given by this Article 6 to the Trustee
or to the Debentureholders shall, to the extent permitted by law, be deemed
cumulative and not exclusive of any thereof or of any other powers and remedies
available to the Trustee or the holders of the Debentures, by judicial
proceedings or otherwise, to enforce the performance or observance of the
covenants and agreements contained in this Indenture, and no delay or omission
of the Trustee or of any holder of any of the Debentures to exercise any right
or power accruing upon any default or Event of Default occurring and continuing
as aforesaid shall impair any such right or power, or shall be construed to be a
waiver of any such default or any acquiescence therein, and, subject to the
provisions of Section 6.04, every power and remedy given by this Article 6 or by
law to the Trustee or to the Debentureholders may be exercised from time to
time, and as often as shall be deemed expedient, by the Trustee or by the
Debentureholders.

          SECTION 6.07.  DIRECTION OF PROCEEDINGS AND WAIVER OF DEFAULTS BY
MAJORITY OF DEBENTUREHOLDERS. The holders of a majority in aggregate principal
amount of the Debentures at the time outstanding determined in accordance with
Section 8.04 shall have the right to direct the time, method and place of
conducting any proceeding for any remedy available to the Trustee or exercising
any trust or power conferred on the Trustee; PROVIDED that (a) such direction
shall not be in conflict with any rule of law or with this Indenture, (b) the
Trustee may take any other action which is not inconsistent with such direction
and (c) the Trustee may decline to take any action that would benefit some
Debentureholders to the detriment of other Debentureholders, or that may involve
the Trustee in personal liability. The holders of a majority in aggregate
principal amount of the Debentures at the time outstanding determined in
accordance with Section 8.04 may, on behalf of the holders of all of the
Debentures, waive any past default or Event of Default hereunder and its
consequences, except (i) a default in the payment of interest (including
Contingent Interest and Additional Interest, if any) on, or the principal of,
the Debentures, (ii) a failure by the Company to convert any Debentures into
Common Stock, (iii) a default in the payment of the Redemption Price pursuant to
Section 3.03, (iv) a default in the payment of the Fundamental Change Repurchase
Price pursuant to Section 3.05 or Company Repurchase Price pursuant to Section
3.06 or (v) a default in respect of a covenant or provision hereof which under
Article 10 cannot be modified or amended without the consent of the holders of
each or all Debentures then outstanding or affected thereby. Upon any such
waiver, the Company, the Trustee and the holders of the Debentures shall be
restored to their former positions and rights hereunder; but no such waiver
shall extend to any subsequent or other default or Event of Default or impair
any right consequent thereon. Whenever any default or Event of Default hereunder
shall have been waived as permitted by this Section 6.07, said default or Event
of Default shall for all purposes of the Debentures and this Indenture be deemed
to have been cured and to be not continuing; but no such waiver shall extend to
any subsequent or other default or Event of Default or impair any right
consequent thereon.

          SECTION 6.08.  NOTICE OF DEFAULTS. The Trustee shall, within ninety
(90) days after the occurrence of a Default or, if later, within fifteen (15)
days after such Default is known to a Trust Officer or after written notice of
the occurrence of such Default is received by the Trustee, mail to all
Debentureholders, as the names and addresses of such holders appear upon the
Debenture Register, notice of all Defaults known to a Trust Officer, unless such
Default shall have been cured or waived before the giving of such notice;
PROVIDED that except in the case of Default in the payment of the principal of
(including any Redemption Price or Repurchase Price

                                       42
<Page>

pursuant to Article 3 for) or interest (including Contingent Interest and
Additional Interest, if any) on any of the Debentures, the Trustee shall be
protected in withholding such notice if and so long as a trust committee of
directors and/or Trust Officers of the Trustee in good faith determines that the
withholding of such notice is in the interests of the Debentureholders.

          SECTION 6.09.  UNDERTAKING TO PAY COSTS. All parties to this Indenture
agree, and each holder of any Debenture by its acceptance thereof shall be
deemed to have agreed, that any court may, in its discretion, require, in any
suit for the enforcement of any right or remedy under this Indenture, or in any
suit against the Trustee for any action taken or omitted by it as Trustee, the
filing by any party litigant in such suit of an undertaking to pay the costs of
such suit and that such court may in its discretion assess reasonable costs,
including reasonable attorneys' fees and expenses, against any party litigant in
such suit, having due regard to the merits and good faith of the claims or
defenses made by such party litigant; PROVIDED that the provisions of this
Section 6.09 (to the extent permitted by law) shall not apply to any suit
instituted by the Trustee, to any suit instituted by any Debentureholder, or
group of Debentureholders, holding in the aggregate more than ten (10) percent
in principal amount of the Debentures at the time outstanding determined in
accordance with Section 8.04, or to any suit instituted by any Debentureholder
for the enforcement of the payment of the principal of (including any Redemption
Price or Repurchase Price pursuant to Article 3 for) or interest (including
Contingent Interest and Additional Interest, if any) on any Debenture on or
after the due date expressed in such Debenture or to any suit for the
enforcement of the right to convert any Debenture in accordance with the
provisions of Article 15.

                                    ARTICLE 7
                                   THE TRUSTEE

          SECTION 7.01.  DUTIES OF TRUSTEE. (a) If an Event of Default known to
the Trustee has occurred and is continuing, the Trustee shall exercise the
rights and powers vested in it by this Indenture and use the same degree of care
and skill in its exercise as a prudent person would exercise or use under the
circumstances in the conduct of such person's own affairs.

          (b) Except during the continuance of an Event of Default known to the
Trustee:

          (i)    the Trustee undertakes to perform such duties and only such
     duties as are specifically set forth in this Indenture and no implied
     covenants or obligations shall be read into this Indenture against the
     Trustee; and

          (ii)   in the absence of bad faith on its part, the Trustee may
     conclusively rely, as to the truth of the statements and the correctness of
     the opinions expressed therein, upon certificates or opinions furnished to
     the Trustee and conforming to the requirements of this Indenture. However,
     in the case of certificates or opinions specifically required by any
     provision hereof to be furnished to it, the Trustee shall examine the
     certificates and opinions to determine whether or not they conform to the
     requirements of this Indenture (but need not confirm or investigate the
     accuracy of mathematical calculations or other facts stated therein).

                                       43
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          (c) The Trustee may not be relieved from liability for its own
negligent action, its own negligent failure to act or its own wilful misconduct,
except that:

          (i)    this paragraph does not limit the effect of paragraph (b) of
     this Section;

          (ii)   the Trustee shall not be liable for any error of judgment made
     in good faith by a Trust Officer unless it is proved that the Trustee was
     negligent in ascertaining the pertinent facts;

          (iii)  the Trustee shall not be liable with respect to any action it
     takes or omits to take in good faith in accordance with a direction
     received by it pursuant to Section 6.07; and

          (iv)   no provision of this Indenture shall require the Trustee to
     expend or risk its own funds or otherwise incur financial liability in the
     performance of any of its duties hereunder or in the exercise of any of its
     rights or powers, if it shall have reasonable grounds to believe that
     repayment of such funds or adequate indemnity against such risk or
     liability is not reasonably assured to it.

          (d) Every provision of this Indenture that in any way relates to the
Trustee is subject to paragraphs (a), (b) and (c) of this Section.

          (e) The Trustee shall not be liable for interest on any money received
by it except as the Trustee may agree in writing with the Company.

          (f) Money held in trust by the Trustee need not be segregated from
other funds except to the extent required by law.

          (g) Every provision of this Indenture relating to the conduct or
affecting the liability of or affording protection to the Trustee shall be
subject to the provisions of this Section and to the provisions of the Trust
Indenture Act.

          SECTION 7.02.  RIGHTS OF TRUSTEE. (a) The Trustee may conclusively
rely and shall be protected in acting or refraining from acting on any document
believed by it, in good faith, to be genuine and to have been signed or
presented by the proper Person. The Trustee need not investigate any fact or
matter stated in the document.

          (b) Before the Trustee acts or refrains from acting, it may require an
Officers' Certificate or an Opinion of Counsel. The Trustee shall not be liable
for any action it takes or omits to take in good faith in reliance on the
Officers' Certificate or Opinion of Counsel.

          (c) The Trustee may act through agents and shall not be responsible
for the misconduct or negligence of any agent appointed with due care.

          (d) The Trustee shall not be liable for any action it takes or omits
to take in good faith which it believes to be authorized or within its rights or
powers; PROVIDED, HOWEVER, that the Trustee's conduct does not constitute wilful
misconduct or negligence.

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<Page>

          (e) The Trustee may consult with counsel of its selection, and the
advice or opinion of counsel with respect to legal matters relating to this
Indenture and the Debentures shall be full and complete authorization and
protection from liability in respect of any action taken, omitted or suffered by
it hereunder in good faith and in accordance with the advice or opinion of such
counsel.

          (f) The Trustee shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, consent, order, approval, bond, debenture,
note or other paper or document, but the Trustee, in its discretion, may make
such further inquiry or investigation into such facts or matters as it may see
fit, and, if the Trustee shall determine to make such further inquiry or
investigation, it shall be entitled to examine the books, records and premises
of the Company, personally or by agent or attorney at the sole cost of the
Company and shall incur no liability or additional liability of any kind by
reason of such inquiry or investigation.

          (g) The Trustee shall be under no obligation to exercise any of the
rights or powers vested in it by this Indenture at the request or direction of
any of the holders pursuant to this Indenture, unless such holders shall have
offered to the Trustee security or indemnity satisfactory to the Trustee against
the costs, expenses and liabilities which might be incurred by it in compliance
with such request or direction.

          (h) The rights, privileges, protections, immunities and benefits given
to the Trustee, including, without limitation, its right to be indemnified, are
extended to, and shall be enforceable by, the Trustee in each of its capacities
hereunder, and each agent, custodian and other Person employed to act hereunder.

          (i) The Trustee may request that the Company deliver an Officers'
Certificate setting forth the names of individuals and/or titles of officers
authorized at such time to take specified actions pursuant to this Indenture,
which Officers' Certificate may be signed by any Person authorized to sign an
Officers' Certificate, including any Person specified as so authorized in any
such certificate previously delivered and not superseded.

          (j) The grant of any permissive rights, power or authority hereunder
to the Trustee shall not be construed to be a duty.

          SECTION 7.03.  INDIVIDUAL RIGHTS OF TRUSTEE. The Trustee in its
individual or any other capacity may become the owner or pledgee of Debentures
and may otherwise deal with the Company or its Affiliates with the same rights
it would have if it were not Trustee. Any Paying Agent or Debenture Registrar
may do the same with like rights. However, the Trustee must comply with Sections
7.09 and 7.10.

          SECTION 7.04.  TRUSTEE'S DISCLAIMER. The Trustee shall not be
responsible for and makes no representation as to the validity or adequacy of
this Indenture or the Debentures, it shall not be accountable for the Company's
use of the proceeds from the Debentures, and it shall not be responsible for any
statement of the Company in this Indenture or in any document issued in
connection with the sale of the Debentures or in the Debentures other than the
Trustee's certificate of authentication. The Trustee shall not be charged with
knowledge of any Default or

                                       45
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Event of Default under Section 6.01, or other matter, unless either (a) a Trust
Officer shall have actual knowledge thereof or (b) the Trustee shall have
received notice thereof in accordance with Section 16.04 from the Company or any
holder.

          SECTION 7.05.  REPORTS BY TRUSTEE TO HOLDERS. Within thirty (30) days
after each June 15 beginning with the June 15 following the date of this
Indenture, the Trustee shall mail to each holder a brief report dated as of such
June 15 that complies with Section 313(a) of the Trust Indenture Act if and to
the extent required thereby. The Trustee shall also comply with Section 313(b)
of the Trust Indenture Act.

          A copy of each report at the time of its mailing to holders shall be
filed with the Commission and each stock exchange (if any) on which the
Debentures are listed. The Company agrees to notify promptly the Trustee
whenever the Debentures become listed on any stock exchange and of any delisting
thereof.

          SECTION 7.06.  COMPENSATION AND INDEMNITY. The Company shall pay to
the Trustee from time to time such reasonable compensation for its services
hereunder as the Company and the Trustee shall from time to time agree in
writing. The Trustee's compensation shall not be limited by any law on
compensation of a trustee of an express trust. The Company shall reimburse the
Trustee upon request for all reasonable out-of-pocket expenses incurred or made
by it, including costs of collection, in addition to the compensation for its
services as the Company and the Trustee shall, from time to time, agree in
writing. Such expenses shall include the reasonable compensation and expenses,
disbursements and advances of the Trustee's agents, counsel, accountants and
experts. The Company shall indemnify the Trustee or any predecessor Trustee and
their agents against any and all loss, liability, claim, damage or expense
(including reasonable attorneys' fees) incurred by or in connection with the
administration of this trust and the performance of its duties hereunder. The
Trustee shall notify the Company of any claim for which it may seek indemnity
promptly upon obtaining actual knowledge thereof. The Company shall defend the
claim and the indemnified party shall provide reasonable cooperation at the
Company's expense in the defense. Such indemnified parties may have separate
counsel and the Company shall pay the reasonable fees and expenses of such
counsel; PROVIDED, HOWEVER, that the Company shall not be required to pay the
fees and expenses of such counsel if it assumes such indemnified parties'
defense unless, in such indemnified parties' reasonable judgment, there is a
conflict of interest between the Company and such parties in connection with
such defense. The Company need not reimburse any expense or indemnify against
any loss, liability or expense incurred by an indemnified party through such
party's own wilful misconduct, negligence or bad faith. The Company need not pay
for any settlement made without its written consent, which consent shall not be
unreasonably withheld.

          To secure the Company's payment obligations in this Section, the
Trustee shall have a lien prior to the Debentures on all money or property held
or collected by the Trustee other than money or property held in trust to pay
principal of and interest (including Contingent Interest and Additional
Interest, if any) on particular Debentures.

          The Company's indemnification and payment obligations pursuant to this
Section shall survive the satisfaction or discharge of this Indenture, any
rejection or termination of this Indenture under any Bankruptcy Law or the
resignation or removal of the Trustee. Without

                                       46
<Page>

prejudice to any other rights available to the Trustee under applicable law,
when the Trustee incurs expenses after the occurrence of a Default specified in
Section 6.01(l) or 6.01(m) with respect to the Company, the expenses are
intended to constitute expenses of administration under the Bankruptcy Law.

          SECTION 7.07.  REPLACEMENT OF TRUSTEE. (a) The Trustee may resign at
any time by so notifying the Company. The holders of a majority in principal
amount of the Debentures then outstanding hereunder determined in accordance
with Section 8.04 may remove the Trustee by so notifying the Trustee and may
appoint a successor Trustee. The Company shall remove the Trustee if:

          (i)    the Trustee fails to comply with Section 7.09;

          (ii)   the Trustee is adjudged bankrupt or insolvent;

          (iii)  a receiver or other public officer takes charge of the Trustee
     or its property; or

          (iv)   the Trustee otherwise becomes incapable of acting.

          (b) If the Trustee resigns or is removed by the Company or by the
holders of a majority in principal amount of the Debentures then outstanding
determined in accordance with Section 8.04 and such holders do not reasonably
promptly appoint a successor Trustee, or if a vacancy exists in the office of
Trustee for any reason (the Trustee in such event being referred to herein as
the retiring Trustee), the Company shall promptly appoint a successor Trustee.

          (c) A successor Trustee shall deliver a written acceptance of its
appointment to the retiring Trustee and to the Company. Thereupon the
resignation or removal of the retiring Trustee shall become effective, and the
successor Trustee shall have all the rights, powers and duties of the Trustee
under this Indenture. The successor Trustee shall mail a notice of its
succession to holders. The retiring Trustee shall promptly transfer all property
held by it as Trustee to the successor Trustee, subject to the lien provided for
in Section 7.06.

          (d) If a successor Trustee does not take office within sixty (60) days
after the retiring Trustee resigns or is removed, the retiring Trustee, at the
Company's expense, or the holders of 10% in principal amount of the Debentures
then outstanding determined in accordance with Section 8.04 may petition at the
expense of the Company any court of competent jurisdiction for the appointment
of a successor Trustee.

          (e) If the Trustee fails to comply with Section 7.01, unless the
Trustee's duty to resign is stayed as provided in Section 310(b) of the Trust
Indenture Act, any holder who has been a bona fide holder of a Debenture for at
least six (6) months may petition any court of competent jurisdiction for the
removal of the Trustee and the appointment of a successor Trustee.

          (f) Notwithstanding the replacement of the Trustee pursuant to this
Section, the Company's obligations under Section 7.06 shall continue for the
benefit of the retiring Trustee.

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<Page>

          SECTION 7.08.  SUCCESSOR TRUSTEE BY MERGER. If the Trustee
consolidates with, merges or converts into, or transfers all or substantially
all its corporate trust business or assets to, another corporation or banking
association, the resulting, surviving or transferee corporation without any
further act shall be the successor Trustee.

          In case at the time such successor or successors by merger, conversion
or consolidation to the Trustee shall succeed to the trusts created by this
Indenture any of the Debentures shall have been authenticated but not delivered,
any such successor to the Trustee may adopt the certificate of authentication of
any predecessor trustee, and deliver such Debentures so authenticated; and in
case at that time any of the Debentures shall not have been authenticated, any
successor to the Trustee may authenticate such Debentures either in the name of
any predecessor hereunder or in the name of the successor to the Trustee; and in
all such cases such certificates shall have the full force which it is anywhere
in the Debentures or in this Indenture provided that the certificate of the
Trustee shall have.

          SECTION 7.09.  ELIGIBILITY; DISQUALIFICATION. The Trustee shall at all
times satisfy the requirements of Section 310(a) of the Trust Indenture Act. The
Trustee shall have a combined capital and surplus of at least $50,000,000 as set
forth in its most recent published annual report of condition. The Trustee shall
comply with Section 310(b) of the Trust Indenture Act, subject to its right to
apply for a stay of its duty to resign under the penultimate paragraph of
Section 310(b) of the Trust Indenture Act; PROVIDED, HOWEVER, that there shall
be excluded from the operation of Section 310(b)(1) of the Trust Indenture Act
any indenture or indentures under which other securities or certificates of
interest or participation in other securities of the Company are outstanding if
the requirements for such exclusion set forth in Section 310(b)(1) of the Trust
Indenture Act are met.

          SECTION 7.10.  PREFERENTIAL COLLECTION OF CLAIMS AGAINST COMPANY. The
Trustee shall comply with Section 311(a) of the Trust Indenture Act, excluding
any creditor relationship listed in Section 311(b) of the Trust Indenture Act. A
Trustee who has resigned or been removed shall be subject to Section 311(a) of
the Trust Indenture Act to the extent indicated.

                                    ARTICLE 8
                              THE DEBENTUREHOLDERS

          SECTION 8.01.  ACTION BY DEBENTUREHOLDERS. Whenever in this Indenture
it is provided that the holders of a specified percentage in aggregate principal
amount of the Debentures may take any action (including the making of any demand
or request, the giving of any notice, consent or waiver or the taking of any
other action), the fact that at the time of taking any such action, the holders
of such specified percentage have joined therein may be evidenced (a) by any
instrument or any number of instruments of similar tenor executed by
Debentureholders in person or by agent or proxy appointed in writing, (b) by the
record of the holders of Debentures voting in favor thereof at any meeting of
Debentureholders duly called and held in accordance with the provisions of
Article 9 or (c) by a combination of such instrument or instruments and any such
record of such a meeting of Debentureholders. Whenever the Company or the
Trustee solicits the taking of any action by the holders of the Debentures, the
Company or the Trustee may fix in advance of such solicitation, a date as the

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record date for determining holders entitled to take such action. The record
date shall not be more than fifteen (15) days prior to the date of commencement
of solicitation of such action.

          SECTION 8.02.  PROOF OF EXECUTION BY DEBENTUREHOLDERS. Subject to the
provisions of Section 7.01, 7.02 and 9.05, proof of the execution of any
instrument by a Debentureholder or its agent or proxy shall be sufficient if
made in accordance with such reasonable rules and regulations as may be
prescribed by the Trustee or in such manner as shall be satisfactory to the
Trustee. The holding of Debentures shall be proved by the registry of such
Debentures or by a certificate of the Debenture Registrar.

          The record of any Debentureholders' meeting shall be proved in the
manner provided in Section 9.06.

          SECTION 8.03.  WHO ARE DEEMED ABSOLUTE OWNERS. The Company, the
Trustee, any Paying Agent, any Conversion Agent and any Debenture Registrar may
deem the Person in whose name a Debenture shall be registered upon the Debenture
Register to be, and may treat it as, the absolute owner of such Debenture
(whether or not such Debenture shall be overdue and notwithstanding any notation
of ownership or other writing thereon made by any Person other than the Company
or any Debenture Registrar) for the purpose of receiving payment of or on
account of the principal of and interest on such Debenture, for conversion of
such Debenture and for all other purposes; and none of the Company, the Trustee,
any Paying Agent or any Conversion Agent nor any Debenture Registrar shall be
affected by any notice to the contrary. All such payments so made to any such
holder, or upon his order, shall be valid, and, to the extent of the sum or sums
so paid, effectual to satisfy and discharge the liability for monies payable
upon such Debenture.

          SECTION 8.04.  COMPANY OWNED DEBENTURES DISREGARDED. In determining
whether the holders of the requisite aggregate principal amount of Debentures
have concurred in any direction, consent, waiver or other action under this
Indenture, Debentures which are owned by the Company or any other obligor on the
Debentures or any Affiliate of the Company shall be disregarded and deemed not
to be outstanding solely for the purpose of any such determination; PROVIDED
that for the purposes of determining whether the Trustee shall be protected in
relying on any such direction, consent, waiver or other action, only Debentures
which a Trust Officer knows are so owned shall be so disregarded. Debentures so
owned which have been pledged in good faith may be regarded as outstanding for
the purposes of this Section 8.04 if the pledgee shall establish to the
satisfaction of the Trustee the pledgee's right to vote such Debentures and that
the pledgee is not the Company, any other obligor on the Debentures or any
Affiliate of the Company. In the case of a dispute as to such right, any
decision by the Trustee taken upon the advice of counsel shall fully protect the
Trustee. Upon request of the Trustee, the Company shall furnish to the Trustee
promptly an Officers' Certificate listing and identifying all Debentures, if
any, known by the Company to be owned or held by or for the account of any of
the above described Persons, and, subject to Section 7.01, the Trustee shall be
entitled to accept such Officers' Certificate as conclusive evidence of the
facts therein set forth and of the fact that all Debentures listed therein are
outstanding for the purpose of any such determination.

          SECTION 8.05.  REVOCATION OF CONSENTS, FUTURE HOLDERS BOUND. At any
time prior to (but not after) the evidencing to the Trustee, as provided in
Section 8.01, of the taking of

                                       49
<Page>

any action by the holders of the percentage in aggregate principal amount of the
Debentures specified in this Indenture in connection with such action, any
holder of a Debenture which is shown by the evidence to be included in the
Debentures the holders of which have consented to such action may, by filing
written notice with the Trustee at its Corporate Trust Office and upon proof of
holding as provided in Section 8.02, revoke such action so far as concerns such
Debenture. Except as aforesaid, any such action taken by the holder of any
Debenture shall be conclusive and binding upon such holder and upon all future
holders and owners of such Debenture and of any Debentures issued in exchange or
substitution therefor, irrespective of whether any notation in regard thereto is
made upon such Debenture or any Debenture issued in exchange or substitution
therefor.

                                    ARTICLE 9
                          MEETINGS OF DEBENTUREHOLDERS

          SECTION 9.01.  PURPOSE OF MEETINGS.

          A meeting of Debentureholders may be called at any time and from time
to time pursuant to the provisions of this Article 9 for any of the following
purposes:

          (a) to give any notice to the Company or to the Trustee or to give any
directions to the Trustee permitted under this Indenture, or to consent to the
waiving of any default or Event of Default hereunder and its consequences, or to
take any other action authorized to be taken by Debentureholders pursuant to any
of the provisions of Article 6;

          (b) to remove the Trustee and nominate a successor trustee pursuant to
the provisions of Article 7;

          (c) to consent to the execution of an indenture or indentures
supplemental hereto pursuant to the provisions of Section 10.02; or

          (d) to take any other action authorized to be taken by or on behalf of
the holders of any specified aggregate principal amount of the Debentures under
any other provision of this Indenture or under applicable law.

          Nothing in this Article 9 shall be construed (i) to prevent or
preclude the Trustee from otherwise calling or conducting any meeting of holders
of Debentures at which a formal vote shall not be conducted (such as, but not
limited to, an informational meeting), in any alternative manner that the
Trustee shall deem appropriate or (ii) to require that a meeting be called or
conducted in order to obtain, or in connection with, any particular request,
demand, authorization, direction, notice, consent, waiver or other action
provided in this Indenture to be made, given or taken by holders of Debentures.

          SECTION 9.02.  CALL OF MEETINGS BY TRUSTEE. The Trustee may at any
time call a meeting of Debentureholders to take any action specified in Section
9.01, to be held at such time and at such place as the Trustee shall determine;
PROVIDED that any such meeting may be conducted by telephone conference in a
manner reasonable designed to be substantially consistent with the procedures
set forth in this Article 9. Notice of every meeting of the Debentureholders,
setting forth the time and the place of such meeting and in general terms the

                                       50
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action proposed to be taken at such meeting and the establishment of any Record
Date pursuant to Section 8.01, shall be mailed to holders of Debentures at their
addresses as they shall appear on the Debenture Register. Such notice shall also
be mailed to the Company. Such notices shall be mailed not less than twenty (20)
nor more than ninety (90) days prior to the date fixed for the meeting.

          Any meeting of Debentureholders shall be valid without notice if the
holders of all Debentures then outstanding are present in person or by proxy or
if notice is waived before or after the meeting by the holders of all Debentures
outstanding, and if the Company and the Trustee are either present by duly
authorized representatives or have, before or after the meeting, waived notice.

          SECTION 9.03.  CALL OF MEETINGS BY COMPANY OR DEBENTUREHOLDERS. In
case at any time the Company, pursuant to a resolution of the Board of
Directors, or the holders of at least 10% in aggregate principal amount of the
Debentures then outstanding determined in accordance with Section 8.04, shall
have requested the Trustee to call a meeting of Debentureholders, by written
request setting forth in reasonable detail the action proposed to be taken at
the meeting, and the Trustee shall not have mailed the notice of such meeting
within twenty (20) days after receipt of such request, then the Company or such
Debentureholders may determine the time and the place for such meeting and may
call such meeting to take any action authorized in Section 9.01, by mailing
notice thereof as provided in Section 9.02.

          SECTION 9.04.  QUALIFICATIONS FOR VOTING. To be entitled to vote at
any meeting of Debentureholders a Person shall (a) be a holder of one or more
Debentures on the Record Date pertaining to such meeting or (b) be a Person
appointed by an instrument in writing as proxy by a holder of one or more
Debentures on the Record Date pertaining to such meeting. The only Persons who
shall be entitled to be present or to speak at any meeting of Debentureholders
shall be the Persons entitled to vote at such meeting and their counsel and any
representatives of the Trustee and its counsel and any representatives of the
Company and its counsel. Notwithstanding the foregoing or any other term to the
contrary in this Article 9, nothing in this Article 9 shall preclude or prevent
the Trustee from calling or conducting any meeting of Debentureholders (whether
pursuant to this Article 9 or otherwise) at which the Company is not allowed or
entitled to be present.

          SECTION 9.05.  REGULATIONS. Notwithstanding any other provisions of
this Indenture, the Trustee may make such reasonable regulations as it may deem
advisable for any meeting of Debentureholders, in regard to proof of the holding
of Debentures and of the appointment of proxies, and in regard to the
appointment and duties of inspectors of votes, the submission and examination of
proxies, certificates and other evidence of the right to vote, and such other
matters concerning the conduct of the meeting as it shall think fit.

          The Trustee shall, by an instrument in writing, appoint a temporary
chairman of the meeting, unless the meeting shall have been called by the
Company or by Debentureholders as provided in Section 9.03, in which case the
Company or the Debentureholders calling the meeting, as the case may be, shall
in like manner appoint a temporary chairman. A permanent chairman and a
permanent secretary of the meeting shall be elected by vote of the holders of a

                                       51
<Page>

majority in principal amount of the Debentures represented at the meeting and
entitled to vote at the meeting.

          Subject to the provisions of Section 8.04, at any meeting each
Debentureholder or proxyholder shall be entitled to one vote for each $1,000
principal amount of Debentures held or represented by him; PROVIDED that no vote
shall be cast or counted at any meeting in respect of any Debenture challenged
as not outstanding and ruled by the chairman of the meeting to be not
outstanding. The chairman of the meeting shall have no right to vote other than
by virtue of Debentures held by him or instruments in writing as aforesaid duly
designating him as the proxy to vote on behalf of other Debentureholders. Any
meeting of Debentureholders duly called pursuant to the provisions of Section
9.02 or 9.03 may be adjourned from time to time by the holders of a majority of
the aggregate principal amount of Debentures represented at the meeting, whether
or not constituting a quorum, and the meeting may be held as so adjourned
without further notice.

          SECTION 9.06.  VOTING. The vote upon any resolution submitted to any
meeting of Debentureholders shall be by written ballot on which shall be
subscribed the signatures of the holders of Debentures or of their
representatives by proxy and the outstanding principal amount of the Debentures
held or represented by them. The permanent chairman of the meeting shall appoint
two inspectors of votes who shall count all votes cast at the meeting for or
against any resolution and who shall make and file with the secretary of the
meeting their verified written reports in duplicate of all votes cast at the
meeting. A record in duplicate of the proceedings of each meeting of
Debentureholders shall be prepared by the secretary of the meeting and there
shall be attached to said record the original reports of the inspectors of votes
on any vote by ballot taken thereat and affidavits by one or more Persons having
knowledge of the facts setting forth a copy of the notice of the meeting and
showing that said notice was mailed as provided in Section 9.02. The record
shall show the principal amount of the Debentures voting in favor of or against
any resolution. The record shall be signed and verified by the affidavits of the
permanent chairman and secretary of the meeting and one of the duplicates shall
be delivered to the Company (except in the case of a meeting at which the
Company was not allowed to be present) and the other to the Trustee to be
preserved by the Trustee, the latter to have attached thereto the ballots voted
at the meeting.

          Any record so signed and verified shall be conclusive evidence of the
matters therein stated.

          SECTION 9.07.  NO DELAY OF RIGHTS BY MEETING. Nothing contained in
this Article 9 shall be deemed or construed to authorize or permit, by reason of
any call of a meeting of Debentureholders or any rights expressly or impliedly
conferred hereunder to make such call, any hindrance or delay in the exercise of
any right or rights conferred upon or reserved to the Trustee or to the
Debentureholders under any of the provisions of this Indenture or of the
Debentures.

                                       52
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                                   ARTICLE 10
                             SUPPLEMENTAL INDENTURES

          SECTION 10.01. SUPPLEMENTAL INDENTURES WITHOUT CONSENT OF
DEBENTUREHOLDERS. The Company and the Trustee may, from time to time, and at any
time enter into an indenture or indentures supplemental hereto so as to amend
this Indenture or the Debentures without notice to or consent of any
Debentureholder for one or more of the following purposes:

          (a) to make provision with respect to the conversion rights of the
holders of Debentures pursuant to the requirements of Section 15.06 or the
repurchase obligations of the Company pursuant to the requirements of Section
3.08(h);

          (b) to convey, transfer, assign, mortgage or pledge to the Trustee as
security for the Debentures, any property or assets;

          (c) to add guarantees or guarantors with respect to the Debentures;

          (d) to secure the Debentures;

          (e) to evidence the succession of another Person to the Company, or
successive successions, and the assumption by the successor Person of the
covenants, agreements and obligations of the Company pursuant to Article 11;

          (f) to surrender any right or power conferred upon the Company under
this Indenture;

          (g) to add to the covenants of the Company such further covenants,
restrictions or conditions for the benefit of the holders of Debentures, and to
make the occurrence, or the occurrence and continuance, of a default in any such
additional covenants, restrictions or conditions a Default or an Event of
Default permitting the enforcement of all or any of the several remedies
provided in this Indenture as herein set forth; PROVIDED that in respect of any
such additional covenant, restriction or condition, such supplemental indenture
may provide for a particular period of grace after default (which period may be
shorter or longer than that allowed in the case of other defaults) or may
provide for an immediate enforcement upon such default or may limit the remedies
available to the Trustee upon such default;

          (h) to provide for uncertificated Debentures in addition to, or in
place of, certificated Debentures (PROVIDED, HOWEVER, that the uncertificated
Debentures are issued in registered form for purposes of Section 163(f) of the
Internal Revenue Code of 1986, as amended), in a manner such that the
uncertificated Debentures are described in Section 163(f)(2)(b) of the Internal
Revenue Code of 1986, as amended;

          (i) to cure any ambiguity or omission or to correct or supplement any
provision contained herein or in any supplemental indenture that may be
defective or inconsistent with any other provisions contained herein or in any
supplemental indenture;

                                       53
<Page>

          (j) to evidence and provide for the acceptance of appointment of a
successor Trustee with respect to this Indenture and the Debentures;

          (k) to modify, eliminate or add to the provisions of this Indenture to
such extent as shall be necessary to effect the qualifications of this Indenture
or any supplemental indenture under the Trust Indenture Act, or under any
similar federal statute hereafter enacted;

          (l) to increase the Conversion Rate or increase the consideration
payable to any holder of Debentures, PROVIDED that no such increase individually
or in the aggregate with all other such increases has or will have an adverse
effect on the interests of the Debentureholders;

          (m) to make other changes to this Indenture or forms or terms of the
Debentures, PROVIDED that no such change individually or in the aggregate with
all other such changes has or will have an adverse effect on the rights of the
Debentureholders; or

          (n) to comply with any requirement of the SEC in connection with the
qualification of the Debenture on any supplemental Debenture under the Trust
Indenture Act.

          Upon the written request of the Company, accompanied by a copy of the
resolutions of the Board of Directors certified by the Company's Secretary or
Assistant Secretary authorizing the execution of any supplemental indenture, the
Trustee is hereby authorized to join with the Company in the execution of any
such supplemental indenture, to make any further appropriate agreements and
stipulations that may be therein contained and to accept the conveyance,
transfer, assignment, mortgage or pledge of any property or asset thereunder,
but the Trustee shall not be obligated to, but may in its discretion, enter into
any supplemental indenture that affects the Trustee's own rights, duties or
immunities under this Indenture or otherwise.

          Any supplemental indenture authorized by the provisions of this
Section 10.01 may be executed by the Company and the Trustee without the consent
of the holders of any of the Debentures at the time outstanding, notwithstanding
any of the provisions of Section 10.02.

          Notwithstanding any other provision of this Indenture or the
Debentures, the Registration Rights Agreement and the obligation to pay
Additional Interest thereunder may be amended, modified or waived in accordance
with the provisions of the Registration Rights Agreement.

          After a supplemental indenture under this Section 10.01 becomes
effective, the Company shall mail to Debentureholders a notice briefly
describing such supplemental indenture. The failure to give such notice to all
Debentureholders, or any defect therein, shall not impair or affect the validity
of a supplemental indenture under this Section 10.01.

          SECTION 10.02. SUPPLEMENTAL INDENTURE WITH CONSENT OF
DEBENTUREHOLDERS. With the consent (evidenced as provided in Article 8) of the
holders of at least a majority in aggregate principal amount of the Debentures
at the time outstanding determined in accordance with Section 8.04, the Company
and the Trustee may, from time to time and at any time, enter into an indenture
or indentures supplemental hereto for the purpose of adding any provisions to or
changing in any manner or eliminating any of the provisions of this Indenture or
any

                                       54
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supplemental indenture or of modifying in any manner the rights of the holders
of the Debentures; PROVIDED that without the consent of each Debentureholder
affected thereby no such supplemental indenture shall (i) change the Stated
Maturity of any Debenture, or reduce the stated rate or extend the stated time
for payment of interest (including Contingent Interest and Additional Interest,
if any) on any Debenture, or reduce the principal amount of any Debenture, or
reduce any amount payable on redemption or repurchase of any Debenture or change
the time at which any Debenture may be redeemed or repurchased, or impair the
right of any Debentureholder to receive payment of principal of and interest
(including Contingent Interest and Additional Interest, if any) on such holder's
Debentures on or after the due dates therefor or to institute suit for the
enforcement of any payment on or with respect to such holder's Debentures, or
make the principal of or interest (including Contingent Interest and Additional
Interest, if any) on any Debenture payable in any coin or currency other than
that provided in the Debentures, or affect the obligation of the Company to
redeem any Debenture on a Redemption Date in a manner adverse to such
Debentureholder, or affect the obligation of the Company to repurchase any
Debenture upon the happening of a Fundamental Change in a manner adverse to such
Debentureholder, or affect the obligation of the Company to repurchase any
Debenture on a Company Repurchase Date in a manner adverse to such
Debentureholder, or impair the right to convert the Debentures into shares of
Common Stock subject to the terms set forth herein, including Section 15.06, or
reduce the number of shares of Common Stock or other property receivable upon
conversion, or modify any of the provisions of this Article 10 or Section 6.07,
except to increase any such percentage or to provide that certain other
provisions of this Indenture cannot be modified or waived without the consent of
the holder of each Debenture so affected, or change any obligation of the
Company to maintain an office or agency in the places and for the purposes set
forth in Section 4.02, reduce the quorum or voting requirements set forth in
Article 9 or (ii) reduce the aforesaid percentage of Debentures, the holders of
which are required to consent to any such supplemental indenture.

          Upon the written request of the Company, accompanied by a copy of the
resolutions of the Board of Directors certified by its Secretary or Assistant
Secretary authorizing the execution of any such supplemental indenture and an
Officers' Certificate and Opinion of Counsel as provided in Section 10.05, and
upon the filing with the Trustee of evidence of the consent of Debentureholders
as aforesaid, the Trustee shall join with the Company in the execution of such
supplemental indenture unless such supplemental indenture affects the Trustee's
own rights, duties or immunities under this Indenture or otherwise, in which
case the Trustee may in its discretion, but shall not be obligated to, enter
into such supplemental indenture.

          It shall not be necessary for the consent of the Debentureholders
under this Section 10.02 to approve the particular form of any proposed
supplemental indenture, but it shall be sufficient if such consent shall approve
the substance thereof.

          After a supplemental indenture under this Section 10.02 becomes
effective, the Company shall mail to Debentureholders a notice briefly
describing such supplemental indenture. The failure to give such notice to all
Debentureholders, or any defect therein, shall not impair or affect the validity
of a supplemental indenture under this Section 10.02.

                                       55
<Page>

          SECTION 10.03. EFFECT OF SUPPLEMENTAL INDENTURE. Any supplemental
indenture executed pursuant to the provisions of this Article 10 shall comply
with the Trust Indenture Act, as then in effect, PROVIDED that this Section
10.03 shall not require such supplemental indenture or the Trustee to be
qualified under the Trust Indenture Act prior to the time such qualification is
in fact required under the terms of the Trust Indenture Act or this Indenture
has been qualified under the Trust Indenture Act, nor shall it constitute any
admission or acknowledgment by any party to such supplemental indenture that any
such qualification is required prior to the time such qualification is in fact
required under the terms of the Trust Indenture Act or this Indenture has been
qualified under the Trust Indenture Act. Upon the execution of any supplemental
indenture pursuant to the provisions of this Article 10, this Indenture shall be
and shall be deemed to be modified and amended in accordance therewith and the
respective rights, limitation of rights, obligations, duties and immunities
under this Indenture of the Trustee, the Company and the holders of Debentures
shall thereafter be determined, exercised and enforced hereunder, subject in all
respects to such modifications and amendments and all the terms and conditions
of any such supplemental indenture shall be and shall be deemed to be part of
the terms and conditions of this Indenture for any and all purposes.

          SECTION 10.04. NOTATION ON DEBENTURES. Debentures authenticated and
delivered after the execution of any supplemental indenture pursuant to the
provisions of this Article 10 may bear a notation in form approved by the
Trustee as to any matter provided for in such supplemental indenture. If the
Company or the Trustee shall so determine, new Debentures so modified as to
conform, in the opinion of the Trustee and the Board of Directors, to any
modification of this Indenture contained in any such supplemental indenture may,
at the Company's expense, be prepared and executed by the Company, authenticated
by the Trustee (or an authenticating agent duly appointed by the Trustee
pursuant to Section 16.13) and delivered in exchange for the Debentures then
outstanding, upon surrender of such Debentures then outstanding. Failure to make
the appropriate notation or to issue a new Debenture shall not affect the
validity of such supplemental indenture.

          SECTION 10.05. TRUSTEE TO SIGN SUPPLEMENTAL INDENTURES. The Trustee
shall sign any supplemental indenture authorized pursuant to this Article 10 if
the supplemental indenture does not adversely affect the rights, duties,
liabilities or immunities of the Trustee. If it does, the Trustee may but need
not sign it. In signing such supplemental indenture, the Trustee shall be
provided with receive indemnity reasonably satisfactory to it and (subject to
Section 7.01) shall be fully protected in relying upon an Officers' Certificate
and an Opinion of Counsel stating that such supplemental indenture is authorized
or permitted by this Indenture and is in compliance with the requirements of
Section 10.03; and in the case of a supplemental indenture pursuant to Section
10.01(l) or Section 10.01(m), the Trustee shall be entitled to receive and shall
be fully protected in relying upon an Opinion of Counsel as to whether such
supplemental indenture has an adverse effect on the rights or interests of
Debentureholders.

                                   ARTICLE 11
                CONSOLIDATION, MERGER, SALE, CONVEYANCE AND LEASE

          SECTION 11.01. COMPANY MAY CONSOLIDATE ON CERTAIN TERMS. Subject to
the provisions of Section 11.02, the Company shall not consolidate or merge with
or into, or convey, transfer or lease, in one transaction or a series of related
transactions, directly or indirectly, all or

                                       56
<Page>

substantially all its assets to any Person unless (i) the resulting, surviving
or transferee Person (the "Successor Company") is the Company, or the resulting,
surviving or transferee Person is a corporation organized and existing under the
laws of the United States of America, any state thereof or the District of
Columbia; (ii) upon any such consolidation, merger, sale, conveyance, transfer
or lease, the due and punctual payment of the principal of and interest
(including Contingent Interest and Additional Interest, if any) on all of the
Debentures, according to their tenor, and the due and punctual performance and
observance of all of the covenants and conditions of this Indenture to be
performed by the Company, shall be expressly assumed, by supplemental indenture
reasonably satisfactory in form to the Trustee, executed and delivered to the
Trustee by the Person (if other than the Company) formed by such consolidation,
or into which the Company shall have been merged, or by the Person that shall
have acquired or leased such property, and such supplemental indenture shall
provide for the applicable conversion rights set forth in Section 15.06 and
(iii) immediately after giving effect to the transaction described above, no
Event of Default, and no event which, after notice or passage of time or both,
would be an Event of Default, shall have occurred and be continuing.

          SECTION 11.02. SUCCESSOR TO BE SUBSTITUTED. (a) In case of any such
consolidation, merger, sale, conveyance, transfer or lease and upon the
assumption by the Successor Company, by supplemental indenture, executed and
delivered to the Trustee and satisfactory in form to the Trustee, of the due and
punctual payment of the principal of and interest (including Contingent Interest
and Additional Interest, if any) on all of the Debentures and the due and
punctual performance of all of the covenants and conditions of this Indenture to
be performed by the Company, as described in Section 11.01(a), the Successor
Company shall succeed to and be substituted for the Company, with the same
effect as if it had been named herein as the party of this first part. The
Successor Company thereupon may cause to be signed, and may issue either in its
own name or in the name of Charles River Associates Incorporated any or all of
the Debentures, issuable hereunder that theretofore shall not have been signed
by the Company and delivered to the Trustee; and, upon the order of the
Successor Company instead of the Company and subject to all the terms,
conditions and limitations in this Indenture prescribed, the Trustee shall
authenticate and shall deliver, or cause to be authenticated and delivered, any
Debentures that previously shall have been signed and delivered by the officers
of the Company to the Trustee for authentication, and any Debentures that the
Successor Company thereafter shall cause to be signed and delivered to the
Trustee for that purpose. All the Debentures so issued shall in all respects
have the same legal rank and benefit under this Indenture as the Debentures
theretofore or thereafter issued in accordance with the terms of this Indenture
as though all of such Debentures had been issued at the date of the execution
hereof. In the event of any such consolidation, merger, sale, conveyance or
transfer (but not in the case of a lease), the Person named as the "COMPANY" in
the first paragraph of this Indenture or any successor that shall thereafter
have become such in the manner prescribed in this Article 11 may be dissolved,
wound up and liquidated at any time thereafter and such Person shall be released
from its liabilities as obligor and maker of the Debentures and from its
obligations under this Indenture.

          In case of any such consolidation, merger, sale, conveyance, transfer
or lease, such changes in phraseology and form (but not in substance) may be
made in the Debentures thereafter to be issued as may be appropriate.

                                       57
<Page>

          SECTION 11.03. OPINION OF COUNSEL TO BE GIVEN TRUSTEE. In the event of
any such consolidation, merger, sale, conveyance, transfer or lease, the Trustee
shall receive an Officers' Certificate and an Opinion of Counsel, each stating
that any such consolidation, merger, sale, conveyance, transfer or lease and any
such supplemental indenture relating to such assumption complies with the
provisions of this Article 11, and such Officers' Certificate and Opinion of
Counsel shall be conclusive evidence as to such compliance with this Article 11.

                                   ARTICLE 12
                     SATISFACTION AND DISCHARGE OF INDENTURE

          SECTION 12.01. DISCHARGE OF INDENTURE. When (a) the Company shall
deliver to the Trustee for cancellation all Debentures theretofore authenticated
(other than any Debentures that have been destroyed, lost or stolen and in lieu
of or in substitution for which other Debentures shall have been authenticated
and delivered) and not theretofore canceled, or (b) all the Debentures not
theretofore canceled or delivered to the Trustee for cancellation shall have
become due and payable and the Company shall deposit with the Trustee, in trust,
cash or, if expressly permitted or required by the terms of the Debentures or
this Indenture, Common Stock or a combination thereof sufficient to pay all
amounts due and owing on Debentures (other than any Debentures that shall have
been mutilated, destroyed, lost or stolen and in lieu of or in substitution for
which other Debentures shall have been authenticated and delivered) not
theretofore canceled or delivered to the Trustee for cancellation, accompanied
by a verification report, as to the sufficiency of the deposited amount, from an
independent certified accountant or other financial professional satisfactory to
the Trustee, and if in either case the Company shall also pay or cause to be
paid all other sums payable hereunder by the Company, then this Indenture shall
cease to be of further effect (except as to (i) remaining rights of registration
of transfer, substitution and exchange and conversion of Debentures, (ii) rights
hereunder of Debentureholders to receive payments of principal of and interest
(including Contingent Interest and Additional Interest, if any) on the
Debentures and the other rights of Debentureholders, as beneficiaries hereof
with respect to the amounts, if any, so deposited with the Trustee, (iii) the
obligations of the Company under Section 7.06 hereof and (iv) the rights, powers
and immunities of the Trustee hereunder and the duties of the Trustee under
Sections 12.02 and 12.04), and the Trustee, on written demand of the Company
accompanied by an Officers' Certificate and an Opinion of Counsel as required by
Section 16.06 and at the cost and expense of the Company, shall execute proper
instruments acknowledging satisfaction of and discharging this Indenture; the
Company, however, hereby agrees to reimburse the Trustee for any costs or
expenses thereafter reasonably and properly incurred by the Trustee and to
compensate the Trustee for any services thereafter reasonably and properly
rendered by the Trustee in connection with this Indenture or the Debentures.

          SECTION 12.02. APPLICATION OF TRUST MONEY. Subject to the provisions
of Section 12.04, all money deposited with the Trustee for payment of the
Debentures pursuant to Section 12.01 shall be held in trust for the sole benefit
of the Debentureholders and such monies shall be applied by the Trustee, in
accordance with the provisions of the Debentures and this Indenture, to the
payment, either directly or through any Paying Agent, to the Persons entitled
thereto, of the principal of and interest (including Contingent Interest and
Additional Interest, if any) on the Debentures for whose payment such money has
been deposited with the Trustee. The Company shall pay and indemnify the Trustee
against any tax, fee or other charge imposed

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<Page>

or assessed against all money deposited with the Trustee pursuant to Section
12.01 (other than income taxes and franchise taxes incurred or payable by the
Trustee and such other taxes, fees or charges incurred or payable by the Trustee
that are not directly the result of the deposit of such money with the Trustee).

          SECTION 12.03. PAYING AGENT TO REPAY MONIES HELD. Upon the
satisfaction and discharge of this Indenture, all monies then held by any Paying
Agent of the Debentures (other than the Trustee) shall, upon written request of
the Company, be repaid to it or paid to the Trustee, and thereupon such Paying
Agent shall be released from all further liability with respect to such monies.

          SECTION 12.04. RETURN OF UNCLAIMED MONIES. Subject to the requirements
of applicable law, any monies deposited with or paid to the Trustee for payment
of the principal of or interest on Debentures and not applied but remaining
unclaimed by the holders of Debentures for two years after the date upon which
the principal of or interest on such Debentures, as the case may be, shall have
become due and payable, shall be repaid to the Company by the Trustee on demand
and all liability of the Trustee shall thereupon cease with respect to such
monies; and the holder of any of the Debentures shall thereafter look only to
the Company for any payment that such holder may be entitled to collect unless
an applicable abandoned property law designates another Person.

                                   ARTICLE 13
         IMMUNITY OF INCORPORATORS, STOCKHOLDERS, OFFICERS AND DIRECTORS

          SECTION 13.01. INDENTURE AND DEBENTURES SOLELY CORPORATE OBLIGATIONS.
No recourse for the payment of the principal of or interest (including
Contingent Interest and Additional Interest, if any) on any Debenture, or for
any claim based thereon or otherwise in respect thereof, and no recourse under
or upon any obligation, covenant or agreement of the Company in this Indenture
or in any supplemental indenture or in any Debenture, or because of the creation
of any indebtedness represented thereby, shall be had against any incorporator,
stockholder, employee, agent, officer, director or subsidiary, as such, past,
present or future, of the Company or of any successor Person, either directly or
through the Company or any successor Person thereto, whether by virtue of any
constitution, statute or rule of law, or by the enforcement of any assessment or
penalty or otherwise; it being expressly understood that all such liability is
hereby expressly waived and released as a condition of, and as a consideration
for, the execution of this Indenture and the issue of the Debentures.

                                   ARTICLE 14
                               CONTINGENT INTEREST

          SECTION 14.01. CONTINGENT INTEREST. Additional interest ("CONTINGENT
INTEREST") will accrue on each Debenture during the period commencing June 20,
2011 and ending December 14, 2011, if the average Trading Price of the
Debentures during the Applicable Five-Day Trading Period immediately preceding
June 20, 2011 equals or exceeds 125% of the principal amount of the Debentures.
Contingent Interest will accrue on each Debenture during an Interest Period,
beginning with the Interest Period commencing on December 15, 2011, if the
average Trading Price of the Debentures during the Applicable Five-Day Trading
Period

                                       59
<Page>

immediately preceding the applicable Interest Period equals or exceeds 125% of
the principal amount of the Debentures. If Contingent Interest accrues during an
Interest Period pursuant to the preceding sentence, the amount of Contingent
Interest payable with respect to such Interest Period per $1,000 principal
amount of Debentures shall equal 0.25% of the average Trading Price during the
Applicable Five-Day Trading Period with respect to such Interest Period.

     The Trustee's sole responsibility pursuant to this Section 14.01 shall be
to obtain the bids for determining the Trading Price of the Debentures for each
Trading Day during the Applicable Five-Day Trading Period and to provide such
information to the Company, to the extent that the Trustee is then the Bid
Solicitation Agent. The Company shall select (with written notice to the
Trustee) the independent nationally recognized securities dealers (none of which
shall be the Company or an Affiliate thereof) from which the secondary market
bids are to be obtained by the Trustee, and the Company shall determine the
Trading Price and whether holders are entitled to receive Contingent Interest,
and if so, provide notice pursuant to Section 14.03. Notwithstanding any term
contained in this Indenture or any other document to the contrary, the Trustee
shall have no responsibilities, duties or obligations for or with respect to (i)
determining whether the Company must pay Contingent Interest or (ii) determining
the amount of Contingent Interest, if any, payable by the Company.

          SECTION 14.02. PAYMENT OF CONTINGENT INTEREST. Contingent Interest for
any Interest Period shall be paid on the immediately succeeding Interest Payment
Date to the Person in whose name any Debenture (or its Predecessor Debenture) is
registered on the Debenture Register at the close of business on the
corresponding Regular Record Date. Contingent Interest due under this Section
14.02 shall be treated for all purposes of this Indenture like any other
interest accruing on the Debentures.

          SECTION 14.03. CONTINGENT INTEREST NOTIFICATION.

          (a) As soon as practicable following the first Business Day of an
Interest Period for which Contingent Interest will be payable pursuant to
Section 14.01, the Company shall deliver notice to the Trustee and issue a press
release stating that Contingent Interest will be paid on the Debentures and
identifying the Interest Period and publish the information on its website on
the World Wide Web.

          (b) On any Interest Payment Date on which Contingent Interest is
payable pursuant to this Article 4, the Company shall deliver notice to the
Trustee, issue a press release stating the amount of such Contingent Interest
and setting the forth the manner in which such amount was calculated and publish
such information on its website on the World Wide Web.

                                   ARTICLE 15
                            CONVERSION OF DEBENTURES

          SECTION 15.01. RIGHT TO CONVERT. (a) Subject to and upon compliance
with the provisions of this Indenture, prior to June 15, 2034, the holder of any
Debenture shall have the right, at such holder's option, to convert the
principal amount of such Debenture, or any portion of such principal amount
which is an integral multiple of $1,000, into fully paid and non-assessable
shares of Common Stock (as such shares shall then be constituted) at the
Conversion

                                       60
<Page>

Rate in effect at such time, by surrender of the Debenture so to be converted in
whole or in part, together with any required funds, under the circumstances
described in this Section 15.01 and in the manner provided in Section 15.02. The
Debentures shall be convertible only during the following periods upon the
occurrence of one of the following events:

          (i)    prior to February 16, 2029, during any fiscal quarter of the
     Company after the fiscal quarter of the Company ending September 3, 2004,
     if the Last Reported Sale Price of the Common Stock for at least twenty
     (20) Trading Days during the period of thirty (30) consecutive Trading Days
     ending on the last Trading Day of the preceding fiscal quarter equals or
     exceeds 125% of the Conversion Price on such Trading Day and, on or after
     February 17, 2029, at any time after the Last Reported Sale Price of the
     Common Stock is equal to or more than 125% of the Conversion Price;

          (ii)   in the event that the Company calls the Debentures for
     redemption, at any time prior to the close of business on the second
     Business Day immediately preceding the Redemption Date; PROVIDED that only
     those Debentures that are called for redemption may be converted following
     such an event;

          (iii)  as provided in Section (b) of this Section 15.01;

          (iv)   during the five (5) Business Day period immediately after any
     three (3) consecutive Trading Day period in which the Trading Price per
     $1,000 principal amount of the Debentures for each day of such three (3)
     day measurement period was less than 98% of the product of the average of
     the Last Reported Sale Price of the Common Stock for each day during such
     three (3) day measurement period and the Conversion Rate, as determined
     following a request by a holder of Debentures in accordance with the
     procedures described below; or

          (v)    upon the occurrence of certain reductions in credit ratings
     as follows:

                 (A) in the event that the Debentures are assigned a credit
          rating by either Moody's Investor Service, Inc. ("MOODY'S") or from
          Standard & Poor's Ratings Services ("STANDARD & POOR'S") when the
          long-term credit rating assigned to the debentures by either Moody's
          or Standard & Poor's is two or more levels below the initial credit
          rating assigned by Moody's or Standard & Poor's, as the case may be;
          or

                 (B) if after either Moody's or Standard & Poor's has assigned
          the debentures a credit rating, such rating is discontinued, suspended
          or withdrawn by such rating agency.

          Notwithstanding the foregoing, if, on the date of any conversion
pursuant to Section 15.01(a)(iv) on or after June 15, 2029, the Last Reported
Sale Price of the Common Stock on the Trading Day prior to the date of such
conversion is greater than 100% but less than 125% of the Conversion Price, the
holders of Debentures surrendered for conversion shall receive, in lieu of
Common Stock based on the Conversion Rate, cash or Common Stock or a combination
of cash or Common Stock, at the Company's option, with a value equal to the
principal amount of the Debentures to be converted plus accrued and unpaid
interest (including

                                       61
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Contingent Interest and Additional Interest, if any), if any, to (but excluding)
the Conversion Date (a "PRINCIPAL VALUE CONVERSION"). Any Common Stock delivered
upon a Principal Value Conversion will be valued at the average of the Last
Reported Sale Price of the Common Stock for a five (5) Trading Day period
starting the third Trading Day following the Conversion Date. If a holder of
Debentures surrenders its Debentures for a Principal Value Conversion, the
Company shall notify such holder by the second Trading Day following the
Conversion Date that it is a Principal Value Conversion and whether the Company
will pay such holder all or a portion of such principal amount and interest
(including Contingent Interest and Additional Interest, if any) in cash, Common
Stock or a combination of cash and Common Stock, and in what percentage. The
Company shall pay such holder any portion of such principal amount and interest
(including Contingent Interest and Additional Interest, if any) to be paid in
cash and deliver Common Stock with respect to any portion of such principal
amount and interest to be paid in Common Stock, no later than the third Business
Day following the determination of the average Last Reported Sale Price of the
Common Stock. The Company shall pay such holder any portion of such principal
amount and interest to be paid in cash, no later than the third (3rd) Business
Day following the determination of the average Last Reported Sale Price of the
Common Stock.

          The Company or its designated agent shall determine on a daily basis
during the time period specified in clause (i) above whether the Debentures
shall be convertible as a result of the occurrence of an event specified in
clause (i) above and, if the Debentures shall be so convertible, the Company
shall promptly deliver to the Trustee (or other Conversion Agent appointed by
the Company) written notice thereof. Whenever the Debentures shall become
convertible pursuant to this Section 15.01, the Company or, at the Company's
request, the Trustee in the name and at the expense of the Company, shall notify
the holders of the event triggering such convertibility in the manner provided
in Section 16.04, and the Company shall also publicly announce such information
by publication on the Company's web site or through such other public medium as
it may use at such time. Any notice so given shall be conclusively presumed to
have been duly given, whether or not the holder receives such notice.

          The Trustee (or other Conversion Agent appointed by the Company) shall
have no obligation to determine the Trading Price under this Section 15.01
unless the Company has requested in writing such a determination; and the
Company shall have no obligation to make such request unless a holder provides
it with reasonable evidence that the Trading Price per $1,000 principal amount
of Debentures would be less than 98% of the product of the Last Reported Sale
Price of the Common Stock and the Conversion Rate. If such evidence is provided,
the Company shall instruct the Trustee (or other Conversion Agent) in writing to
determine the Trading Price of the Debentures beginning on the next Trading Day
and on each successive Trading Day until, and only until, the Trading Price per
$1,000 principal amount of Debentures is greater than or equal to 98% of the
product of the Last Reported Sale Price of the Common Stock and the Conversion
Rate.

          The Trustee shall be entitled at its sole discretion to consult with
the Company and to request the assistance of the Company in connection with the
Trustee's duties and obligations pursuant to this Section 15.01(a), and the
Company agrees, if requested by the Trustee, to cooperate with, and provide
assistance to, the Trustee in carrying out its duties under

                                       62
<Page>

this Section 15.01; PROVIDED, HOWEVER, that nothing herein shall be construed to
relieve the Trustee of its duties pursuant to this Section 15.01(a).

          (b) In addition, if:

          (i)    (A) the Company distributes to all holders of shares of the
     Common Stock any rights, warrants, options or other securities entitling
     them (for a period of not more than forty-five (45) days after the date of
     issuance thereof) to subscribe for or purchase shares of Common Stock, or
     securities convertible into shares of Common Stock (for a period of not
     more than forty-five (45) days after the date of issuance thereof), in
     either case at a price per share or conversion price per share less than
     the average of the Last Reported Sale Prices of the Common Stock for the
     five (5) Trading Days immediately preceding the declaration date of the
     distribution, or (B) the Company distributes to all holders of shares of
     Common Stock assets (including cash), evidences of indebtedness or other
     property or rights to subscribe for or purchase securities of the Company
     (other than those described in clause (A) above), which distribution has a
     per share value as determined by the Company's Board of Directors and set
     forth in a Board Resolution exceeding 5% of the average of the Last
     Reported Sale Prices of the Common Stock for the five (5) Trading Days
     immediately preceding the declaration date of such distribution, then, in
     either case, the Debentures may be surrendered for conversion at any time
     on and after the date that the Company gives notice to the holders of such
     distribution, which notice shall be given not less than twenty (20) days
     prior to the Ex Dividend Date for such distribution, until the earlier of
     the close of business on the Business Day immediately preceding the Ex
     Dividend Date or the date the Company publicly announces that such
     distribution will not take place; PROVIDED, that no holder of a Debenture
     may exercise its right to convert if the holder will otherwise participate
     in such distribution without conversion;

          (ii)   the Company consolidates with or merges with or into another
     Person or is a party to a binding share exchange, in each case pursuant to
     which the Common Stock would be converted into cash or property other than
     securities, then the Debentures may be surrendered for conversion at any
     time from and after the date which is fifteen (15) days prior to the
     anticipated effective date of the transaction and until and including the
     date which is fifteen (15) days after the actual effective date of such
     transaction; and

          (iii)  the Company engages in a reclassification of the Common Stock
     or is a party to a consolidation, merger, binding share exchange or
     transfer of all or substantially all of its assets, in each case pursuant
     to which the Common Stock is converted into cash, securities or other
     property, then at the effective time of such transaction, the right to
     convert a Debenture into shares of Common Stock will be changed into a
     right to convert such Debenture into the kind and amount of cash,
     securities or other property which a holder would have received if the
     holder had converted its Debentures into shares of Common Stock immediately
     prior to the applicable Record Date for such transaction. If the Company
     engages in any transaction described in the preceding sentence, the
     Conversion Rate will not otherwise be adjusted.

                                       63
<Page>

          The Board of Directors shall determine the anticipated effective date
of any transaction described in Section 15.01(b)(ii), and such determination
shall be conclusive and binding on the holders and shall be publicly announced
by the Company by publication on its web site or through such other public
medium as it may use at that time not later than two (2) Business Days prior to
the first fifteen (15) day period referred to therein.

          If any transaction set forth in clause (i), (ii) or (iii) above also
constitutes a Fundamental Change for which a Make-Whole Premium would have been
payable upon the election of a holder of Debentures to require the repurchase of
such Debentures pursuant to Section 3.05, a holder who instead elects to convert
its Debentures pursuant to this Section 15.01 will be entitled to receive (x) at
the option of the Company, shares of Common Stock, cash or a combination thereof
in respect of the Conversion Obligation, plus (y) the Make-Whole Premium, which
may be paid in cash, shares of Common Stock, or a combination thereof.

          (c) A Debenture in respect of which a holder is electing to exercise
its option to require repurchase upon a Fundamental Change pursuant to Section
3.05 or repurchase pursuant to Section 3.06 may be converted only if such holder
withdraws its election in accordance with Section 3.08(d). A holder of
Debentures is not entitled to any rights of a holder of Common Stock until such
holder has converted its Debentures to Common Stock, and only then to the extent
such Debentures are deemed to have been converted to Common Stock under this
Article 15.

          SECTION 15.02. EXERCISE OF CONVERSION PRIVILEGE; ISSUANCE OF COMMON
STOCK ON CONVERSION; NO ADJUSTMENT FOR INTEREST OR DIVIDENDS; SETTLEMENT OF CASH
OR COMMON STOCK UPON CONVERSION. (a) In order to exercise the conversion
privilege with respect to any Debenture in certificated form, the Company must
receive at the office or agency of the Company maintained for that purpose or,
at the option of such holder, the Corporate Trust Office, such Debenture with
the original or facsimile of the form entitled "FORM OF CONVERSION NOTICE" on
the reverse thereof, duly completed and manually signed, together with such
Debentures duly endorsed for transfer, accompanied by the funds, if any,
required by paragraph (d) of this Section 15.02. Such notice shall also state
the name or names (with address or addresses) in which the certificate or
certificates for shares of Common Stock which shall be issuable on such
conversion shall be issued, and shall be accompanied by transfer or similar
taxes, if required pursuant to Section 15.07.

          In order to exercise the conversion privilege with respect to any
interest in a Global Debenture, the beneficial holder must complete, or cause to
be completed, the appropriate instruction form for conversion pursuant to the
Depositary's book-entry conversion program, deliver, or cause to be delivered,
by book-entry delivery an interest in such Global Debenture, furnish appropriate
endorsements and transfer documents if required by the Company or the Trustee or
the Conversion Agent, and pay the funds, if any, required by this Section 15.02
and any transfer or similar taxes if required pursuant to Section 15.07.

          (b) As promptly as practicable after satisfaction of the requirements
for conversion set forth above, subject to compliance with any restrictions on
transfer if shares issuable on conversion are to be issued in a name other than
that of the Debentureholder (as if such transfer were a transfer of the
Debenture (or portion thereof) so converted), the Company

                                       64
<Page>

shall issue and shall deliver to such Debentureholder at the office or agency
maintained by the Company for that purpose or, at the option of such holder, the
Corporate Trust Office, a certificate or certificates for the number of full
shares of Common Stock issuable upon the conversion of such Debenture or portion
thereof as determined by the Company in accordance with the provisions of this
Article 15 and a check or cash (or wire transfer of immediately available funds
to the accounts specified by the Depository Trust Company) in respect of all or
any portion of the Company's Conversion Obligation being satisfied in cash or
any fractional interest in respect of a share of Common Stock arising upon
conversion, calculated by the Company as provided in Section 15.03. In case any
Debenture of a denomination greater than $1,000 shall be surrendered for partial
conversion, subject to Section 2.02, the Company shall execute and the Trustee
shall authenticate and deliver to the holder of the Debenture so surrendered,
without charge to such holder, a new Debenture or Debentures in authorized
denominations in an aggregate principal amount equal to the unconverted portion
of the surrendered Debenture.

          (c) Each conversion shall be deemed to have been effected as to any
such Debenture (or portion thereof) on the first date on which the requirements
set forth above in this Section 15.02 have been satisfied as to such Debenture
(or portion thereof) (such date, the "CONVERSION DATE"), and the Person in whose
name any certificate or certificates for shares of Common Stock shall be
issuable upon such conversion shall be deemed to have become on said date the
holder of record of the shares represented thereby; PROVIDED that any such
surrender on any date when the stock transfer books of the Company shall be
closed shall constitute the Person in whose name the certificates are to be
issued as the record holder thereof for all purposes on the next succeeding day
on which such stock transfer books are open, but such conversion shall be at the
Conversion Rate in effect on the date upon which such requirements shall have
been satisfied.

          (d) Notwithstanding paragraph (f) below, any Debenture or portion
thereof surrendered for conversion during the period from the close of business
on any Regular Record Date to the close of business on the Business Day
preceding the following Interest Payment Date that has not been called for
redemption during such period shall be accompanied by payment, in immediately
available funds or other funds acceptable to the Company, of an amount equal to
the interest (including Contingent Interest and Additional Interest, if any)
otherwise payable on such Interest Payment Date on the principal amount being
converted; PROVIDED that no such payment need be made (1) if the Company has
specified a Redemption Date that is after a Regular Record Date and on or prior
to a date that is two (2) Business Days after the corresponding Interest Payment
Date, (2) if the Company has specified a Repurchase Date following a Fundamental
Change that is after a Regular Record Date and on or prior to a date that is one
(1) Business Day after the corresponding Interest Payment Date or (3) to the
extent of any overdue interest (including Contingent Interest and Additional
Interest, if any), if any overdue interest exists at the time of conversion with
respect to such Debenture. Except as provided above in this Section 15.02, no
payment or other adjustment shall be made for interest (including Contingent
Interest and Additional Interest, if any) accrued on any Debenture (or portion
thereof) converted or for dividends on any shares issued upon the conversion of
such Debenture (or portion thereof) as provided in this Article 15.

                                       65
<Page>

          (e) Upon the conversion of an interest in a Global Debenture, the
Trustee (or other Conversion Agent appointed by the Company), or the Custodian
at the direction of the Trustee (or other Conversion Agent appointed by the
Company), shall make a notation on such Global Debenture as to the reduction in
the principal amount represented thereby. The Company shall notify the Trustee
in writing of any conversions of Debentures effected through any Conversion
Agent other than the Trustee.

          (f) Upon the conversion of a Debenture (or portion thereof), that
portion of the accrued and unpaid interest (including Contingent Interest and
Additional Interest, if any) with respect to the converted Debenture (or portion
thereof) to (but excluding) the Conversion Date shall not be canceled,
extinguished or forfeited, but rather shall be deemed to be paid in full to the
holder thereof through delivery of the Common Stock (together with the cash
payment, if any, in lieu of fractional shares) (or cash or a combination of cash
and Common Stock) in exchange for the Debenture (or portion thereof) being
converted pursuant to the provisions hereof; and the fair market value of such
shares of Common Stock (together with any such cash payment in lieu of
fractional shares) (or cash or a combination of cash and Common Stock) shall be
treated as issued, to the extent thereof, first in exchange for and in
satisfaction of the Company's obligation to pay the principal amount of the
converted Debenture (or portion thereof) and the accrued and unpaid interest
(including Contingent Interest and Additional Interest, if any) to (but
excluding) the Conversion Date, and the balance, if any, of such fair market
value of such Common Stock (and any such cash payment) (or cash or a combination
of cash and Common Stock) shall be treated as issued in exchange for and in
satisfaction of the right to convert the Debenture (or portion thereof) being
converted pursuant to the provisions hereof.

          (g) In the event that the Company receives a Form of Conversion Notice
on or prior to (1) the date on which the Company gives a Redemption Notice with
respect to the applicable Debenture or (2) the date that is ten (10) days prior
to the Stated Maturity (the "FINAL NOTICE DATE"), the following procedures shall
apply:

          (i)    If the Company elects to satisfy all or any portion of its
     obligation to convert the Debentures (the "CONVERSION OBLIGATION") in cash,
     the Company shall notify holders through the Trustee of the dollar amount
     to be satisfied in cash (which must be expressed either as 100% of the
     Conversion Obligation or as a fixed dollar amount) at any time on or before
     the date that is two (2) Business Days following the Conversion Date (the
     "CASH SETTLEMENT NOTICE PERIOD"), unless the Company already has informed
     holders of its election in connection with its Redemption of the Debentures
     under Section 3.01. If the Company timely elects to pay cash for any
     portion of the Common Stock otherwise issuable to holders upon conversion,
     holders may retract the Conversion Notice at any time during the two (2)
     Business Days following the final day of the Cash Settlement Notice Period
     (the "CONVERSION RETRACTION PERIOD"). No such retraction can be made (and a
     Form of Conversion Notice shall be irrevocable) if the Company does not
     elect to deliver cash (other than cash in lieu of fractional shares) in
     lieu of all or a portion of the Common Stock otherwise to be issued. Upon
     the expiration of a Conversion Retraction Period, a Form of Conversion
     Notice shall be irrevocable. If the Company elects to satisfy all or any
     portion of the Conversion Obligation in cash, and the applicable Form of
     Conversion Notice has not been retracted, then settlement (in cash or

                                       66
<Page>

     in cash and shares of Common Stock) will be made through the Conversion
     Agent no later than the tenth (10th) Business Date following the Conversion
     Date to holders timely surrendering Debentures.

          (ii)   If the Company does not elect to satisfy any part of the
     Conversion Obligation in cash (other than cash in lieu of any fractional
     shares), delivery of the Common Stock into which the Debentures are
     converted (and cash in lieu of any fractional shares) shall occur through
     the Conversion Agent no later than the fifth (5th) Business Date following
     the Conversion Date to holders timely surrendering Debentures.

          (h) Settlement amounts will be computed as follows:

          (i)    If the Company elects to satisfy the entire Conversion
     Obligation in Common Stock, it shall deliver to holders that have delivered
     the Conversion Notice giving rise to the Conversion Obligation a number of
     shares of Common Stock equal to (i) the aggregate principal amount of
     Debentures to be converted divided by 1,000, multiplied by (ii) the
     Conversion Rate. In addition, the Company shall pay cash for any fractional
     shares of Common Stock based on the Last Reported Sale Price of the Common
     Stock on the Trading Day immediately preceding the Conversion Date.

          (ii)   If the Company elects to satisfy the entire Conversion
     Obligation in cash, it shall deliver to holders that have delivered the
     Conversion Notice giving rise to the Conversion Obligation cash in an
     amount equal to the product of:

                 (A) a number equal to (i) the aggregate principal amount of
          Debentures to be converted divided by 1,000, multiplied by (ii) the
          Conversion Rate; and

                 (B) the average of the Last Reported Sale Prices of the Common
          Stock for the five (5) consecutive Trading Days (x) immediately
          following the date of the Company's notice of its election to deliver
          cash, if the Company has not given a Redemption Notice, or (y) ending
          on the third (3rd) Trading Day prior to the Conversion Date, in the
          case of a conversion following a Redemption Notice specifying that the
          Company intends to deliver cash upon conversion (each a "CASH
          SETTLEMENT AVERAGING PERIOD").

          (iii)  If the Company elects to satisfy a fixed portion (other than
     100%) of the Conversion Obligation in cash, it will deliver to holders the
     specified cash amount (the "CASH AMOUNT") and a number of shares of Common
     Stock equal to the greater of (i) zero and (ii) the excess, if any, of the
     number of shares of Common Stock calculated as if the Company elected to
     satisfy the entire Conversion Obligation in shares over the number of
     shares equal to the sum, for each day of the applicable Cash Settlement
     Averaging Period, of (x) 20% of the Cash Amount, divided by (y) the Last
     Reported Sale Price of the Common Stock. In addition, the Company shall pay
     cash for all fractional shares of Common Stock based on the Last Reported
     Sale Price of the Common Stock on the Trading Day immediately preceding the
     Conversion Date.

                                       67
<Page>

          In no event shall the amount of cash delivered upon conversion of
Debentures exceed $1,000 per $1,000 principal amount of Debentures to be
converted. Any such excess amount shall be paid by the Company in shares of
Common Stock.

          The Company must determine whether or not it will satisfy all or a
portion of the Conversion Obligation in cash at the time it issues a Redemption
Notice and such notices will state the amount of the Conversion Obligation to be
settled in cash. If a Form of Conversion Notice is received from holders of
Debentures subject to a Redemption Notice after the date that a Redemption
Notice has been issued, such holders may not retract their Conversion Notice.
Settlement (in cash and/or Common Stock) will occur no later than the fifth
(5th) Business Date following the Conversion Date.

          (i) The Company may irrevocably elect, in its sole discretion and
without the consent of holders of the Debentures, by notice to the Trustee and
the holders of the Debentures, to satisfy in cash 100% of the principal amount
of the Debentures converted after the date of such election. Notwithstanding
such election, the Company may satisfy a Conversion Obligation to the extent it
exceeds the principal amount of the Debentures in shares of Common Stock (or
cash in lieu of any fractional shares) pursuant to this Section 15.02.

          SECTION 15.03. CASH PAYMENTS IN LIEU OF FRACTIONAL SHARES. No
fractional shares of Common Stock or scrip certificates representing fractional
shares shall be issued upon conversion of Debentures. If more than one Debenture
shall be surrendered for conversion at one time by the same holder, the number
of full shares that shall be issuable upon conversion shall be computed on the
basis of the aggregate principal amount of the Debentures (or specified portions
thereof to the extent permitted hereby) so surrendered. If any fractional share
of stock would be issuable upon the conversion of any Debenture or Debentures,
the Company shall make an adjustment and payment therefor in cash to the holder
thereof at the Last Reported Sale Price of the Common Stock on the last Trading
Day immediately preceding the day on which the Debentures (or the specified
portions thereof) are deemed to have been converted.

          SECTION 15.04. CONVERSION RATE. Each $1,000 principal amount of the
Debentures shall be convertible into the number of shares of Common Stock
specified in the form of Debenture (herein called the "CONVERSION RATE") set
forth in Exhibit A hereto (initially 25.00 shares), subject to adjustment as
provided in this Article 15. References to Conversion Rate, applicable
Conversion Rate, current Conversion Rate and Conversion Rate then in effect mean
the Conversion Rate in effect on the relevant date.

          SECTION 15.05. ADJUSTMENT OF CONVERSION RATE. The Conversion Rate
shall be adjusted from time to time by the Company as follows:

          (a) If shares of Common Stock are issued as a dividend or distribution
on shares of Common Stock, or if a share split or share combination is effected,
the Conversion Rate will be adjusted based on the following formula:

                                                  OS'
                               CR'=CR SUB(0) X --------
                                               OS SUB(0)

     where,

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<Page>

          CR SUB(0)  =  the Conversion Rate in effect immediately prior to such
                        event

          CR'        =  the Conversion Rate in effect immediately after such
                        event

          OS SUB(0)  =  the number of shares of Common Stock outstanding
                        immediately prior to such event

          OS'        =  the number of shares of Common Stock outstanding
                        immediately after such event

          An adjustment made pursuant to this subsection (a) shall become
effective on the date immediately after (x) the date fixed for the determination
of stockholders entitled to receive such dividend or other distribution or (y)
the date on which such split or combination becomes effective, as applicable. If
any dividend or distribution described in this subsection (a) is declared but
not so paid or made, the Conversion Rate shall again be adjusted to the
Conversion Rate that would then be in effect if such dividend or distribution
had not been declared.

          (b) If any rights, warrants, options or other securities are issued to
all or substantially all of the holders of shares of Common Stock entitling them
for a period of not more than forty-five (45) days after the date of issuance
thereof to subscribe for or purchase shares of Common Stock, or securities
convertible into shares of Common Stock within forty-five (45) days after the
date of issuance thereof, in either case at an exercise price per share or a
conversion price per share less than the Last Reported Sale Price of the Common
Stock on the Business Day immediately preceding the time of announcement of such
issuance, the Conversion Rate will be adjusted based on the following formula:


                                            OS SUB(0) + X
                          CR'=CR SUB(0) X -----------------
                                            OS SUB(0) + Y

     where,

          CR SUB(0)  =  the Conversion Rate in effect immediately prior to such
                        event

          CR'        =  the Conversion Rate in effect immediately after such
                        event

          OS SUB(0)  =  the number of shares of Common Stock outstanding
                        immediately prior to such event

          X          =  the total number of shares of Common Stock issuable
                        pursuant to such rights, warrants, options, other
                        securities or convertible securities

          Y          =  the number of shares of Common Stock equal to the
                        aggregate exercise price or conversion price payable to
                        exercise or convert such rights, warrants, options,
                        other securities or convertible securities divided by
                        the average of the Last Reported Sale Prices of the
                        Common Stock for the ten (10) consecutive Trading Days
                        prior to the Business Day immediately preceding the date
                        of announcement of the issuance of such rights,
                        warrants, options, other securities or convertible
                        securities

          An adjustment made pursuant to this subsection (b) shall be made
successively whenever such rights, warrants, options, other securities or
convertible securities are issued, and

                                       69
<Page>

shall become effective on the day following the date of announcement of such
issuance. If, at the end of the period during which such rights, warrants,
options, other securities or convertible securities are exercisable or
convertible, not all rights, warrants, options, other securities or convertible
securities have been exercised or converted, as the case may be, the adjusted
Conversion Rate shall be immediately readjusted to what it would have been based
upon the number of additional shares of Common Stock actually issued (or the
number of shares of Common Stock actually issued upon conversion of convertible
securities actually issued).

          For purposes of Section 15.01(b) and this Section 15.05(b), in
determining whether such rights, warrants, options, other securities or
convertible securities entitle the holder to subscribe for or purchase or
exercise a conversion right for shares of Common Stock at less than the average
Last Reported Sale Price of the Common Stock, and in determining the aggregate
exercise or conversion price payable for such shares of Common Stock, there
shall be taken into account any consideration received by the Company for such
rights, warrants, options, other securities or convertible securities and any
amount payable on exercise or conversion thereof, with the value of such
consideration, if other than cash, to be determined by the Board of Directors.

          (c) If shares of the Company's capital stock, evidences of the
Company's indebtedness or other assets or property of the Company or its
subsidiaries are distributed to all or substantially all of the holders of
shares of Common Stock, excluding:

          (i)    dividends, distributions and rights, warrants, options, other
     securities or convertible securities referred to in clause (a) or (b)
     above;

          (ii)   dividends or distributions in cash referred to in clause (d)
     below; and

          (iii)  spin-offs described below in this clause (c).

then the Conversion Rate will be adjusted based on the following formula:

                                                    SP SUB(0)
                               CR'=CR SUB(0) X --------------------
                                                 SP SUB(0) - FMV

     where,

          CR SUB(0)  =  the Conversion Rate in effect immediately prior to such
                        distribution

          CR'        =  the Conversion Rate in effect immediately after such
                        distribution

          SP SUB(0)  =  the average of the Last Reported Sale Prices of the
                        Common Stock for the ten (10) consecutive Trading Days
                        prior to the Business Day immediately preceding the
                        record date for such distribution

          FMV        =  the fair market value (as determined in good faith by
                        the Board of Directors of the Company) of the shares of
                        capital stock, evidences of indebtedness, assets or
                        property distributed with respect to each outstanding
                        share of Common Stock on the record date for such
                        distribution

                                       70
<Page>

          An adjustment made pursuant to the above paragraph shall be made
successively whenever any such distribution is made and shall become effective
on the day immediately after the dated fixed for the determination of
shareholders entitled to receive such distribution.

          With respect to an adjustment pursuant to this clause (c) where there
has been a payment of a dividend or other distribution on the Common Stock of
shares of capital stock of any class or series, or similar equity interest, of
or relating to a subsidiary or other business unit of the Company (referred to
as a "SPIN-OFF"), the Conversion Rate in effect immediately before the close of
business on the record date fixed for determination of stockholders entitled to
receive the distribution will be increased based on the following formula:

                                          FMV SUB(0) + MP
                         CR'=CR SUB(0) X ------------------
                                             MP SUB(0)

     where,

          CR SUB(0)  =  the Conversion Rate in effect immediately prior to such
                        distribution

          CR'        =  the Conversion Rate in effect immediately after such
                        distribution

          FMV SUB(0) =  the average of the Last Reported Sale Prices of the
                        capital stock or similar equity interest distributed to
                        holders of shares of Common Stock applicable to one
                        share of Common Stock over the first ten (10)
                        consecutive Trading Days after the effective date of the
                        spin-off

          MP SUB(0)  =  the average of the Last Reported Sale Prices of the
                        Common Stock over the first 10 consecutive Trading Days
                        after the effective date of the spin-off

          The adjustment to the Conversion Rate under the preceding paragraph
will occur on the tenth (10th) Trading Day after the effective date of the
spin-off.

          If any such dividend or distribution described in this subsection (c)
is declared but not paid or made, the Conversion Rate shall again be adjusted to
be the Conversion Rate that would then be in effect if such dividend or
distribution had not been declared.

          (d) If any cash dividend or distribution is paid or made during any of
the Company's quarterly fiscal periods to all or substantially all of the
holders of Common Stock, the Conversion Rate will be adjusted based on the
following formula:

                                                 SP SUB(0)
                                    CR'=CR0 X ---------------
                                               SP SUB(0) - C

     where,

          CR SUB(0)  =  the Conversion Rate in effect immediately prior to the
                        record date for such distribution

                                       71
<Page>

          CR'        =  the Conversion Rate in effect immediately after the
                        record date for such distribution

          SP SUB(0)  =  the average of the Last Reported Sale Prices of the
                        Common Stock for the ten (10) consecutive Trading Days
                        prior to the Business Day immediately preceding the
                        record date of such distribution

          C          =  the amount in cash per share the Company distributes to
                        holders of shares of Common Stock

          An adjustment made pursuant to this subsection (d) shall become
effective on the date immediately after the record date for the determination of
shareholders entitled to receive such dividend or distribution. If any dividend
or distribution described in this subsection (d) is declared but not so paid or
made, the Conversion Rate shall again be adjusted to the Conversion Rate that
would then be in effect if such dividend or distribution had not been declared.

          (e) The Conversion Rate will be increased if the Company or any of its
subsidiaries purchases shares of Common Stock pursuant to a tender offer or
exchange offer which involves an aggregate consideration per share of Common
Stock that exceeds the Last Reported Sale Price of the Common Stock on the
Trading Day next succeeding the last date on which tenders or exchanges may be
made pursuant to the tender offer or exchange offer (the "EXPIRATION TIME"). The
Conversion Rate will be increased based on the following formula:

                                                AC+(SP'XOS')
                             CR'=CR SUB(0) X -----------------
                                               OS SUB(0) XSP'

     where,

          CR SUB(0)  =  the Conversion Rate in effect on the date such tender
                        offer or exchange offer expires

          CR'        =  the Conversion Rate in effect on the day next succeeding
                        the date such tender offer or exchange offer expires

          AC         =  the aggregate value of all cash and other consideration
                        (as determined by the Board of Directors) paid or
                        payable for all shares of Common Stock that the Company
                        or one of its subsidiaries purchases in the tender offer
                        or exchange offer

          OS SUB(0)  =  the number of shares of Common Stock outstanding
                        immediately prior to the date such tender offer or
                        exchange offer expires

          OS'           the number of shares of Common Stock outstanding
                        immediately after the date such tender offer or exchange
                        offer expires

          SP'           the average of the Last Reported Sale Prices of the
                        Common Stock for the ten (10) consecutive Trading Days
                        commencing on the Trading Day next

                                       72
<Page>

                        succeeding the date such tender offer or exchange offer
                        expires

          Any adjustment made pursuant to this subsection (e) shall become
effective on the date immediately following the Expiration Time. If the Company
is obligated to purchase shares of Common Stock pursuant to any such tender or
exchange offer, but the Company is permanently prevented by applicable law from
effecting any such purchases or all such purchases are rescinded, the Conversion
Rate shall again be adjusted to be the Conversion Rate that would be in effect
if such tender or exchange offer had not been made.

          (f) The reclassification of Common Stock into securities other than
Common Stock (other than any reclassification upon an event to which Section
15.06 applies) shall be deemed to involve (a) a distribution of such securities
other than Common Stock to all holders of Common Stock (and the effective date
of such reclassification shall be deemed to be "the date fixed for the
determination of shareholders entitled to receive such distribution" within the
meaning of Section 15.05(c)), and (b) a subdivision, split or combination, as
the case may be, of the number of shares of Common Stock outstanding immediately
prior to such reclassification into the number of shares of Common Stock
outstanding immediately thereafter (and the effective date of such
reclassification shall be deemed to be "the day upon which such split or
combination becomes effective" within the meaning of Section 15.05(a)).

          (g) Notwithstanding the foregoing provisions of Section 15.05, no
adjustment shall be made thereunder, nor shall an adjustment be made to the
ability of a holder of a Debenture to convert, for any distribution described
therein if the holder will otherwise participate in the distribution without
conversion of such holder's Debentures.

          (h) The Company may make such increases in the Conversion Rate, in
addition to those required by clauses (a) through (f) of this Section 15.05, as
the Board of Directors deems advisable to avoid or diminish any income tax to
holders of shares of capital stock of the Company (or rights to acquire such
capital stock) resulting from any dividend or distribution of such capital stock
(or rights to acquire common stock) or from any event treated as such for income
tax purposes.

          To the extent permitted by applicable law, the Company from time to
time may increase the Conversion Rate by any amount for any period of time if
the increase is irrevocable during the period and the Board of Directors shall
have made a determination that such increase would be in the best interests of
the Company, which determination shall be conclusive. Whenever the Conversion
Rate is increased pursuant to the preceding sentence, the Company shall mail to
holders of record of the Debentures a notice of the increase at least fifteen
(15) days prior to the date the increased Conversion Rate takes effect and in
accordance with applicable law and such notice shall state the increased
Conversion Rate and the period during which it will be in effect.

          (i) No adjustment to the Conversion Rate need be made:

          (i)    upon the issuance of any shares of Common Stock pursuant to any
     present or future plan providing for the reinvestment of dividends or
     interest payable on

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     securities of the Company and the investment of additional optional amounts
     in shares of Common Stock under any plan;

          (ii)   upon the issuance of any shares of Common Stock or options or
     rights to purchase shares of Common Stock pursuant to any present or future
     employee, director or consultant incentive benefit plan or program of or
     assumed by the Company or any of its subsidiaries;

          (iii)  upon the issuance of any shares of Common Stock pursuant to any
     option, warrant, right, or exercisable, exchangeable or convertible
     security not described in paragraph (ii) above and outstanding as of the
     Original Issuance Date;

          (iv)   upon the repurchase by the Company of shares of Common Stock
     from its employee protection and deferred compensation trusts or members of
     its senior management upon their resignation or termination of employment;

          (v)    for a change in the par value of the Common Stock; or

          (vi)   for accrued and unpaid interest (including Contingent Interest
     and Additional Interest, if any).

          No adjustment to the Conversion Rate will be required pursuant to this
Indenture in connection with any event, transaction or other occurrence unless
the terms of this Indenture specifically require that such an adjustment be made
in connection with such event, transaction or other occurrence.

          (j) All adjustments to the Conversion Rate under this Article 15 shall
be made by the Company and shall be calculated to the nearest one ten thousandth
(1/10,000) of a share.

          (k) Whenever the Conversion Rate is adjusted as herein provided, the
Company shall promptly file with the Trustee and any Conversion Agent other than
the Trustee an Officers' Certificate setting forth the Conversion Rate after
such adjustment and setting forth a brief statement of the facts requiring such
adjustment. Unless and until a Trust Officer of the Trustee shall have received
such Officers' Certificate, the Trustee shall not be deemed to have knowledge of
any adjustment of the Conversion Rate and may assume that the last Conversion
Rate of which it has knowledge is still in effect. Promptly after delivery of
such certificate, the Company shall prepare a notice of such adjustment of the
Conversion Rate setting forth the adjusted Conversion Rate and the date on which
each adjustment becomes effective and shall mail such notice of such adjustment
of the Conversion Rate to the holder of each Debenture at its last address
appearing on the Debenture Register provided for in Section 2.04, within twenty
(20) days after execution thereof. Failure to deliver such notice shall not
affect the legality or validity of any such adjustment.

          (l) In any case in which this Section 15.05 provides that an
adjustment shall become effective immediately after (1) a record date or Stock
Record Date for an event, (2) the date fixed for the determination of
stockholders entitled to receive a dividend or distribution pursuant to Section
15.05(a), (3) a date fixed for the determination of stockholders entitled to
receive rights, warrants, options or other securities pursuant to Section
15.05(b) or (4) the

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Expiration Time for any tender or exchange offer pursuant to Section 15.05(e),
(each a "DETERMINATION DATE"), the Company may elect to defer until the
occurrence of the applicable Adjustment Event (as hereinafter defined) (x)
issuing to the holder of any Debenture (or portion thereof) converted after such
Determination Date and before the occurrence of such Adjustment Event, the
additional shares of Common Stock or other securities issuable upon such
conversion by reason of the adjustment required by such Adjustment Event over
and above the Common Stock issuable upon such conversion before giving effect to
such adjustment and (y) paying to such holder any amount in cash in lieu of any
fraction pursuant to Section 15.03; PROVIDED that in the case of an adjustment
made pursuant to Section 15.05(d) with respect to a distribution of shares of
capital stock of, or similar equity interest in, a subsidiary or other business
unit of the Company, the Company may defer the issuance of such additional
shares and cash payment, if any, until the third (3rd) Business Day immediately
following the last day of the twenty (20) consecutive Trading Day period
commencing on the fifth (5th) Trading Day after the Ex Dividend Date. For
purposes of this Section 15.05(l), the term "ADJUSTMENT EVENT" shall mean:

          (i)    in any case referred to in clause (1) hereof, the occurrence of
     such event;

          (ii)   in any case referred to in clause (2) hereof, the date any such
     dividend or distribution is paid or made;

          (iii)  in any case referred to in clause (3) hereof, the date of
     expiration of such rights, warrants, options or other securities (or the
     conversion period of any convertible securities issued upon exercise
     thereof); and

          (iv)   in any case referred to in clause (4) hereof, the date a sale
     or exchange of Common Stock pursuant to such tender or exchange offer is
     consummated and becomes irrevocable.

          (m) For purposes of this Section 15.05, the number of shares of Common
Stock at any time outstanding shall not include shares held in the treasury of
the Company but shall include shares issuable in respect of scrip certificates
issued in lieu of fractions of shares of Common Stock. The Company will not pay
any dividend or make any distribution on shares of Common Stock held in the
treasury of the Company.

          (n) Notwithstanding anything in this Indenture to the contrary, in no
event shall the Conversion Rate be adjusted so that the Conversion Price would
be less than $0.01.

          SECTION 15.06. EFFECT OF RECLASSIFICATION, CONSOLIDATION, MERGER OR
SALE. If any of the following events occur, namely (i) any reclassification or
change of the outstanding shares of Common Stock (other than a subdivision or
combination to which Section 15.05(a) applies), (ii) any consolidation, merger
or combination of the Company with another Person as a result of which holders
of Common Stock shall be entitled to receive stock, other securities or other
property or assets (including cash) with respect to or in exchange for such
Common Stock or (iii) any sale or conveyance of all or substantially all of the
properties and assets of the Company to any other Person as a result of which
holders of Common Stock shall be entitled to receive stock, other securities or
other property or assets (including cash) with respect to or in exchange for
such Common Stock, then the Company or the successor or purchasing Person, as

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the case may be, shall execute with the Trustee a supplemental indenture (which
shall comply with the Trust Indenture Act as in force at the date of execution
of such supplemental indenture) providing that each Debenture shall be
convertible into the kind and amount of shares of stock, other securities or
other property or assets (including cash) receivable upon such reclassification,
change, consolidation, merger, combination, sale or conveyance by a holder of a
number of shares of Common Stock issuable upon conversion of such Debentures
(assuming, for such purposes, a sufficient number of treasury shares and
authorized and unissued shares of Common Stock are available to convert all such
Debentures) immediately prior to such reclassification, change, consolidation,
merger, combination, sale or conveyance assuming such holder of Common Stock did
not exercise his rights of election, if any, as to the kind or amount of stock,
other securities or other property or assets (including cash) receivable upon
such reclassification, change, consolidation, merger, combination, sale or
conveyance (PROVIDED that, if the kind or amount of stock, other securities or
other property or assets (including cash) receivable upon such reclassification,
change, consolidation, merger, combination, sale or conveyance is not the same
for each share of Common Stock in respect of which such rights of election shall
not have been exercised (a "NON-ELECTING SHARE"), then for the purposes of this
Section 15.06 the kind and amount of stock, other securities or other property
or assets (including cash) receivable upon such reclassification, change,
consolidation, merger, combination, sale or conveyance for each non-electing
share shall be deemed to be the kind and amount so receivable per share by a
plurality of the non-electing shares). Such supplemental indenture shall provide
for adjustments which shall be as nearly equivalent as may be practicable to the
adjustments provided for in this Article 15.

          The Company shall cause notice of the execution of such supplemental
indenture to be mailed to each holder of Debentures, at its address appearing on
the Debenture Register provided for in Section 2.04, within twenty (20) days
after execution thereof. Failure to deliver such notice shall not affect the
legality or validity of such supplemental indenture.

          The above provisions of this Section shall similarly apply to
successive reclassifications, changes, consolidations, mergers, combinations,
sales and conveyances.

          If this Section 15.06 applies to any event or occurrence, Section
15.05 shall not apply.

          SECTION 15.07. TAXES ON SHARES ISSUED. The issue of stock certificates
on conversions of Debentures shall be made without charge to the converting
Debentureholder for any documentary, stamp or similar issue or transfer tax in
respect of the issue thereof. The Company shall not, however, be required to pay
any such tax which may be payable in respect of any transfer involved in the
issue and delivery of such certificates in any name other than that of the
holder of any Debenture converted, and the Company shall not be required to
issue or deliver any such stock certificate unless and until the Person or
Persons requesting the issue thereof shall have paid to the Company the amount
of such tax or shall have established to the satisfaction of the Company that
such tax has been paid.

          SECTION 15.08. RESERVATION OF SHARES, SHARES TO BE FULLY PAID;
COMPLIANCE WITH GOVERNMENTAL REQUIREMENTS; LISTING OF COMMON STOCK. The Company
shall provide, free from preemptive rights, out of its authorized but unissued
shares or shares held in treasury,

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sufficient shares of Common Stock to provide for the conversion of the
Debentures from time to time as such Debentures are presented for conversion.

          Before taking any action which would cause an adjustment increasing
the Conversion Rate to an amount that would cause the Conversion Price to be
reduced below the then par value, if any, of the shares of Common Stock issuable
upon conversion of the Debentures, the Company will take all corporate action
which may, in the opinion of its counsel, be necessary in order that the Company
may validly and legally issue such shares of Common Stock at such adjusted
Conversion Rate.

          The Company covenants that all shares of Common Stock which may be
issued upon conversion of Debentures will upon issue be fully paid and
nonassessable by the Company and free from all taxes, Liens and charges with
respect to the issue thereof.

          Subject to the terms of the Registration Rights Agreement, the Company
covenants that, if any shares of Common Stock to be provided for the purpose of
conversion of Debentures hereunder require registration with or approval of any
governmental authority under any federal or state law before such shares may be
validly issued upon conversion, the Company will in good faith and as
expeditiously as possible, to the extent then permitted by the rules and
interpretations of the Commission (or any successor thereto), endeavor to secure
such registration or approval, as the case may be.

          The Company further covenants that, if at any time the Common Stock
shall be listed on the Nasdaq National Market or any national securities
exchange or other automated quotation system, the Company will, if permitted by
the rules of such market, exchange or automated quotation system, list and keep
listed, so long as the Common Stock shall be so listed on such market, exchange
or automated quotation system, all Common Stock issuable upon conversion of the
Debentures; PROVIDED that if the rules of such market, exchange or automated
quotation system permit the Company to defer the listing of such Common Stock
until the first conversion of the Debentures into Common Stock in accordance
with the provisions of this Indenture, the Company covenants to list such Common
Stock issuable upon conversion of the Debentures in accordance with the
requirements of such market, exchange or automated quotation system at such
time.

          SECTION 15.09. RESPONSIBILITY OF TRUSTEE. The Trustee and any other
Conversion Agent shall not at any time be under any duty or responsibility to
any holder of Debentures to determine the Conversion Rate or whether any facts
exist which may require any adjustment of the Conversion Rate, or with respect
to the nature or extent or calculation of any such adjustment when made, or with
respect to the method employed, or herein or in any supplemental indenture
provided to be employed, in making the same. The Trustee and any other
Conversion Agent shall not be accountable with respect to the validity or value
(or the kind or amount) of any shares of Common Stock, or of any securities or
property, which may at any time be issued or delivered upon the conversion of
any Debenture; and the Trustee and any other Conversion Agent make no
representations with respect thereto. Neither the Trustee nor any Conversion
Agent shall be responsible for any failure of the Company to issue, transfer or
deliver any shares of Common Stock or stock certificates or other securities or
property or cash upon the surrender of any Debenture for the purpose of
conversion or to comply with any of the

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duties, responsibilities or covenants of the Company contained in this Article
15. Without limiting the generality of the foregoing, neither the Trustee nor
any Conversion Agent shall be under any responsibility to determine the
correctness of any provisions contained in any supplemental indenture entered
into pursuant to Section 15.06 relating either to the kind or amount of shares
of stock or securities or property (including cash) receivable by
Debentureholders upon the conversion of their Debentures after any event
referred to in such Section 15.06 or to any adjustment to be made with respect
thereto, but, subject to the provisions of Section 7.02, may accept as
conclusive evidence of the correctness of any such provisions, and shall be
protected in relying upon, the Officers' Certificate (which the Company shall be
obligated to file with the Trustee prior to the execution of any such
supplemental indenture) with respect thereto.

          SECTION 15.10. NOTICE TO HOLDERS PRIOR TO CERTAIN ACTIONS.

          In case:

          (a) the Company shall declare a dividend (or any other distribution)
on its Common Stock that would require an adjustment in the Conversion Rate
pursuant to Section 15.05; or

          (b) the Company shall authorize the granting to the holders of all or
substantially all of the shares of Common Stock of rights, warrants, options or
other securities to subscribe for or purchase any share of any class of capital
stock of the Company or any other rights, warrants, options or other securities
of the Company; or

          (c) of any reclassification or reorganization of the Common Stock
(other than a subdivision or combination of the outstanding Common Stock, or a
change in par value, or from par value to no par value, or from no par value to
par value), or of any consolidation or merger to which the Company is a party
and for which approval of any stockholders of the Company is required, or of the
sale or transfer of all or substantially all of the assets of the Company; or

          (d) of the voluntary or involuntary dissolution, liquidation or
winding up of the Company;

the Company shall cause to be filed with the Trustee and to be mailed to each
holder of Debentures at its address appearing on the Debenture Register provided
for in Section 2.04, as promptly as possible but in any event at least ten (10)
days prior to the applicable date hereinafter specified, a notice stating (x)
the date on which a record is to be taken for the purpose of such dividend,
distribution or grant, or, if a record is not to be taken, the date as of which
the holders of Common Stock of record to be entitled to such dividend,
distribution or grant are to be determined, or (y) the date on which such
reclassification, consolidation, merger, sale, transfer, dissolution,
liquidation or winding up is expected to become effective or occur, and the date
as of which it is expected that holders of Common Stock of record shall be
entitled to exchange their Common Stock for securities or other property
deliverable upon such reclassification, consolidation, merger, sale, transfer,
dissolution, liquidation or winding up. Failure to give such notice, or any
defect therein, shall not affect the legality or validity of such dividend,

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distribution, grant, reclassification, consolidation, merger, sale, transfer,
dissolution, liquidation or winding up.

          SECTION 15.11. SHAREHOLDER RIGHTS PLAN. If the Company adopts a rights
plan while Debentures remain outstanding, Debentureholders will receive, upon
conversion of their Debentures, in addition to shares of Common Stock, rights
under the Company's stockholder rights agreement unless, prior to conversion,
the rights have expired, terminated or been redeemed or unless the rights have
separated from the Common Stock. If the rights provided for in the rights plan
adopted by the Company have separated from the Common Stock in accordance with
the provisions of the applicable stockholder rights agreement so that the
Debentureholders would not be entitled to receive any rights in respect of
Common Stock issuable upon conversion of the Debentures, the Conversion Rate
will be adjusted at the time of separation as if the Company had distributed, to
all holders of Common Stock, shares of capital stock, evidences of indebtedness
or other assets or property pursuant to Section 15.05(c), subject to
readjustment upon the subsequent expiration, termination or redemption of the
rights. In lieu of any such adjustment, the Company may amend such applicable
stockholder rights agreement to provide that upon conversion of the Debentures
the holders will receive, in addition to shares of Common Stock issuable upon
such conversion, the rights which would have attached to such shares of Common
Stock if the rights had not become separated from the Common Stock under such
applicable stockholder rights agreement. To the extent that the Company adopts
any future stockholder rights agreement, upon conversion of the Debentures into
shares of Common Stock, a Debentureholder shall receive, in addition to shares
of Common Stock, the rights under the future stockholder rights agreement
whether or not the rights have separated from shares of Common Stock at the time
of conversion and no adjustment will be made in accordance with Section 15.05(c)
or otherwise.

                                   ARTICLE 16
                            MISCELLANEOUS PROVISIONS

          SECTION 16.01. INTENTIONALLY OMITTED.

          SECTION 16.02. PROVISIONS BINDING ON SUCCESSORS. All the covenants,
stipulations, promises and agreements by the Company contained in this Indenture
shall bind its successors and assigns whether so expressed or not. All
agreements of the Trustee in this Indenture shall bind its successors and
assigns whether so expressed or not.

          SECTION 16.03. OFFICIAL ACTS BY SUCCESSOR CORPORATION. Any act or
proceeding by any provision of this Indenture authorized or required to be done
or performed by any board, committee or officer of the Company shall and may be
done and performed with like force and effect by the like board, committee or
officer of any Person that shall at the time be the lawful sole successor of the
Company.

          SECTION 16.04. ADDRESSES FOR NOTICES, ETC.Any notice or demand which
by any provision of this Indenture is required or permitted to be given or
served by the Trustee or by the holders of Debentures on the Company shall be
deemed to have been sufficiently given or made, for all purposes, if given or
served by being deposited postage prepaid by registered or certified mail in a
post office letter box or sent by telecopier transmission addressed as follows:

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Charles River Associates Incorporated, 200 Clarendon Street, T-33, Boston,
Massachusetts 02116, Attention: Chief Financial Officer, Facsimile: (617)
425-3790. Any notice, direction, request or demand hereunder to or upon the
Trustee shall be deemed to have been sufficiently given or made, for all
purposes, if given or served by being deposited, postage prepaid, by registered
or certified mail in a post office letter box or sent by telecopier transmission
addressed to the Corporate Trust Office of the Trustee, Facsimile: (617)
603-6683 (PROVIDED, HOWEVER, that any such notice, direction, request or demand
shall not be deemed to have been received by the Trustee, and the Trustee shall
not be charged with notice thereof, until actually received by the Trustee at
such address).

          The Company or the Trustee, by notice to the other and the
Debentureholders, may designate additional or different addresses for subsequent
notices or communications.

          Any notice or communication mailed to a Debentureholder shall be
mailed to him by first class mail, postage prepaid, at his address as it appears
on the Debenture Register and shall be sufficiently given to him if so mailed
within the time prescribed. Any notice so given will be deemed to have been
given to such Debentureholder on the date of such mailing.

          Failure to mail a notice or communication to a Debentureholder or any
defect in it shall not affect its sufficiency with respect to other
Debentureholders. If a notice or communication is mailed in the manner provided
above, it is duly given, whether or not the addressee receives it.

          SECTION 16.05. GOVERNING LAW. This Indenture and each Debenture shall
be deemed to be a contract made under the laws of the State of New York, and for
all purposes shall be construed in accordance with the laws of the State of New
York (including Section 5-1401 of the New York General Obligations Law or any
successor to such statute).

          SECTION 16.06. EVIDENCE OF COMPLIANCE WITH CONDITIONS PRECEDENT,
CERTIFICATES TO TRUSTEE. Upon any application or demand by the Company to the
Trustee to take any action under any of the provisions of this Indenture, the
Company shall furnish to the Trustee an Officers' Certificate stating that, in
the opinion of the signers, all conditions precedent, if any, provided for in
this Indenture relating to the proposed action have been complied with, and an
Opinion of Counsel stating that, in the opinion of such counsel, all such
conditions precedent have been complied with.

          Each certificate or opinion provided for in this Indenture and
delivered to the Trustee with respect to compliance with a condition or covenant
provided for in this Indenture shall include: (1) a statement that each Person
making such certificate or opinion has read such covenant or condition; (2) a
brief statement as to the nature and scope of the examination or investigation
upon which the statement or opinion contained in such certificate or opinion is
based; (3) a statement that, in the opinion of each such Person, he has made
such examination or investigation as is necessary to enable him to express an
informed opinion as to whether or not such covenant or condition has been
complied with; and (4) a statement as to whether or not, in the opinion of each
such Person, such condition or covenant has been complied with.

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          SECTION 16.07. LEGAL HOLIDAYS. In any case in which the date of
maturity of interest on or principal of the Debentures or the Redemption Date of
any Debenture or any Repurchase Date with respect to any Debenture will not be a
Business Day, then payment of such interest on or principal of the Debentures
need not be made on such date, but may be made on the next succeeding Business
Day with the same force and effect as if made on the date of maturity or the
Redemption Date or the Repurchase Date, as the case may be, and no interest
(including Contingent Interest and Additional Interest, if any) shall accrue for
the period from and after such date.

          SECTION 16.08. COMPANY RESPONSIBLE FOR MAKING CALCULATIONS. Unless
otherwise specified in this Indenture, the Company will be responsible for
making all calculations called for under the Debentures. These calculations
include, but are not limited to, determination of the Last Reported Sale Price
of the Common Stock and the Closing Trading Price of the Common Stock, the
amount of accrued and unpaid interest payable on the Debentures and the
Conversion Rate of the Debentures. The Company will make these calculations in
good faith and, absent manifest error, these calculations will be final and
binding on the Debentureholders. Promptly after the calculation thereof, the
Company will provide to each of the Trustee and the Conversion Agent an
Officers' Certificate setting forth a schedule of its calculations, and each of
the Trustee and the Conversion Agent is entitled to conclusively rely upon the
accuracy of such calculations without independent verification. The Trustee will
forward the Company's calculations to any holder upon the request of such
holder.

          SECTION 16.09. TRUST INDENTURE ACT. This Indenture is hereby made
subject to, and shall be governed by, the provisions of the Trust Indenture Act
required to be part of and to govern indentures qualified under the Trust
Indenture Act, which are incorporated by reference in and made a part of this
Indenture; PROVIDED that this Section 16.09 shall not require this Indenture or
the Trustee to be qualified under the Trust Indenture Act prior to the time such
qualification is in fact required under the terms of the Trust Indenture Act,
nor shall it constitute any admission or acknowledgment by any party to this
Indenture that any such qualification is required prior to the time such
qualification is in fact required under the terms of the Trust Indenture Act. If
any provision hereof limits, qualifies or conflicts with another provision
hereof which is required to be included in an indenture qualified under the
Trust Indenture Act, such required provision shall control. The following Trust
Indenture Act terms have the following meanings: "Commission" means the
Commission; "indenture securities" means the Debentures; "indenture security
holder" means a Debentureholder; "indenture to be qualified" means this
Indenture; "indenture trustee" means the Trustee; and "obligor" on the indenture
securities means the Company and any other obligor on the indenture securities.

          SECTION 16.10. NO SECURITY INTEREST CREATED. Except as provided in
Section 7.06, nothing in this Indenture or in the Debentures, expressed or
implied, shall be construed to constitute a security interest under the Uniform
Commercial Code or similar legislation, as now or hereafter enacted and in
effect, in any jurisdiction in which property of the Company or its subsidiaries
is located.

          SECTION 16.11. BENEFITS OF INDENTURE. Nothing in this Indenture or in
the Debentures, express or implied, shall give to any Person, other than the
parties hereto, any Paying Agent, any authenticating agent, any Debenture
Registrar and their successors hereunder

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<Page>

and the holders of Debentures any benefit or any legal or equitable right,
remedy or claim under this Indenture.

          SECTION 16.12. TABLE OF CONTENTS, HEADINGS, ETC.  The table of
contents, cross-reference sheet and the titles and headings of the Articles and
Sections of this Indenture have been inserted for convenience of reference only,
are not to be considered a part hereof, and shall in no way modify or restrict
any of the terms or provisions hereof.

          SECTION 16.13. AUTHENTICATING AGENT. The Trustee may appoint an
authenticating agent that shall be authorized to act on its behalf, and subject
to its direction, in the authentication and delivery of Debentures in connection
with the original issuance thereof and transfers and exchanges of Debentures
hereunder, including under Sections 2.03, 2.07, 2.08, 2.10, 3.02 and 3.08, as
fully to all intents and purposes as though the authenticating agent had been
expressly authorized by this Indenture and those Sections to authenticate and
deliver Debentures. For all purposes of this Indenture, the authentication and
delivery of Debentures by the authenticating agent shall be deemed to be
authentication and delivery of such Debentures "by the Trustee" and a
certificate of authentication executed on behalf of the Trustee by an
authenticating agent shall be deemed to satisfy any requirement hereunder or in
the Debentures for the Trustee's certificate of authentication. Such
authenticating agent shall at all times be a Person eligible to serve as trustee
hereunder pursuant to Section 7.09.

          Any corporation into which any authenticating agent may be merged or
converted or with which it may be consolidated, or any corporation resulting
from any merger, consolidation or conversion to which any authenticating agent
shall be a party, or any corporation succeeding to the corporate trust business
of any authenticating agent, shall be the successor of the authenticating agent
hereunder, if such successor corporation is otherwise eligible under this
Section 16.13, without the execution or filing of any paper or any further act
on the part of the parties hereto or the authenticating agent or such successor
corporation.

          Any authenticating agent may at any time resign by giving written
notice of resignation to the Trustee and to the Company. The Trustee may at any
time terminate the agency of any authenticating agent by giving written notice
of termination to such authenticating agent and to the Company. Upon receiving
such a notice of resignation or upon such a termination, or in case at any time
any authenticating agent shall cease to be eligible under this Section, the
Trustee shall either promptly appoint a successor authenticating agent or itself
assume the duties and obligations of the former authenticating agent under this
Indenture and, upon such appointment of a successor authenticating agent, if
made, shall give written notice of such appointment of a successor
authenticating agent to the Company and shall mail notice of such appointment of
a successor authenticating agent to all holders of Debentures as the names and
addresses of such holders appear on the Debenture Register.

          The Company agrees to pay to the authenticating agent from time to
time such reasonable compensation for its services as shall be agreed upon in
writing between the Company and the authenticating agent.

          The provisions of Sections 7.02, 7.03, 7.04 and 8.03 and this Section
16.13 shall be applicable to any authenticating agent.

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          SECTION 16.14. EXECUTION IN COUNTERPARTS. This Indenture may be
executed in any number of counterparts, each of which shall be an original, but
such counterparts shall together constitute but one and the same instrument.

          SECTION 16.15. SEVERABILITY. In case any provision in this Indenture
or in the Debentures shall be invalid, illegal or unenforceable, then (to the
extent permitted by law) the validity, legality and enforceability of the
remaining provisions shall not in any way be affected or impaired thereby.

                                   ARTICLE 17
                                  SUBORDINATION

          SECTION 17.01. AGREEMENT TO SUBORDINATE. The Company agrees, and each
holder of Debentures by accepting a Debenture agrees, that the Indebtedness
evidenced by the Debenture is subordinated in right of payment, to the extent
and in the manner provided in this Article 17, to the prior payment in full in
cash or other consideration satisfactory to holders of Senior Debt of all Senior
Debt (whether outstanding on the date hereof or hereafter created, incurred,
assumed or guaranteed), and that the subordination is for the benefit of the
holders of Senior Debt.

          SECTION 17.02. LIQUIDATION, DISSOLUTION, BANKRUPTCY. Upon any
distribution to creditors of the Company in a liquidation or dissolution of the
Company or in a bankruptcy, reorganization, insolvency, receivership or similar
proceeding relating to the Company or its property, in an assignment for the
benefit of creditors or any marshaling of the Company's assets and liabilities:

          (a) holders of Senior Debt shall be entitled to receive payment in
     full of all obligations due in respect of such Senior Debt (including
     interest after the commencement of any such proceeding at the rate
     specified in the applicable Senior Debt) in cash or other consideration
     satisfactory to the holders of the Senior Debt before holders of Debentures
     shall be entitled to receive any payment with respect to the Debentures;
     and

          (b) until all Senior Debt is paid in full in cash or other
     consideration satisfactory to the holders of the Senior Debt, any
     distribution to which holders of Debentures would be entitled but for this
     Article 17 shall be made to holders of Senior Debt, as their interests may
     appear.

          SECTION 17.03. DEFAULT ON SENIOR DEBT AND/OR DESIGNATED SENIOR DEBT.

          (a) In the event of any default in payment of the principal of or
premium, if any, or interest on, or any other payment obligation under any
Senior Debt beyond any applicable grace period with respect thereto (a "PAYMENT
DEFAULT"), then, until all such payments due in respect of such Senior Debt have
been paid in full in cash or other consideration satisfactory to holders of
Senior Debt or such default shall have been cured or waived or shall have ceased
to exist, no payment shall be made by the Company with respect to the principal
of or interest (including Contingent Interest and Additional Interest, if any)
on the Debentures or to acquire

                                       83
<Page>

any of the Debentures (including any purchase pursuant to the purchase right of
a holder upon a Fundamental Change).

          (b) In addition, if the Trustee shall receive written notice from one
or more holders of Designated Senior Debt or one or more representatives of such
holder or holders that there has occurred and is continuing under such
Designated Senior Debt, or any agreement pursuant to which such Designated
Senior Debt is issued, any default (other than a Payment Default), which default
shall not have been cured or waived, giving the holders of such Designated
Senior Debt the right to declare such Designated Senior Debt immediately due and
payable (a "PAYMENT BLOCKAGE NOTICE"), then, anything contained in this
Indenture to the contrary notwithstanding, no payment on account of the
principal of or interest (including Contingent Interest and Additional Interest,
if any) on the Securities, and no repurchase or other acquisition of the
Securities, shall be made by or on behalf of the Company during the period (the
"PAYMENT BLOCKAGE PERIOD") commencing on the date of receipt of the Payment
Blockage Notice and ending on the earlier of 179 calendar days thereafter or the
date on which such non-Payment Default is cured or waived.

          Notwithstanding the provisions described in the immediately preceding
sentence (but subject to the provisions contained in Section 17.1 and the first
sentence of this Section 17.3), unless the holder(s) of such Designated Senior
Debt or the representative(s) of such holder(s) shall have accelerated the
maturity of such Designated Senior Debt, the Company may resume payments on the
Debentures after the end of such Payment Blockage Period. No new Payment
Blockage Period may be commenced unless 360 calendar days have elapsed since the
effectiveness of the prior Payment Blockage Notice. No default under Designated
Senior Debt that is not a Payment Default that existed or was continuing on the
date of delivery of any Payment Blockage Notice delivered to the Trustee shall
be, or be made, the basis of a subsequent Payment Blockage Notice.

          SECTION 17.04. ACCELERATION OF DEBENTURES. If payment of the
Debentures is to be accelerated because of an Event of Default (other than an
Event of Default with respect to the Company specified in Section 6.01(k) or
(l)), the Company shall promptly notify holders of Designated Senior Debt or
trustee(s) of such Designated Senior Debt before the acceleration. In the event
of the acceleration of the Debentures because of an Event of Default, the
Company may not make any payment or distribution to the Trustee or any
Debentureholder in respect of obligations with respect to the Debentures until
ten (10) days after holders of Designated Senior Debt or trustee(s) of such
Designated Senior Debt receive notice of such acceleration pursuant to the
immediately preceding sentence and thereafter only to the extent such payment or
distribution is not otherwise prohibited by the terms of this Article 17.

          SECTION 17.05. WHEN DISTRIBUTION MUST BE PAID OVER. In the event that
the Trustee, any holder of Debentures or any other person receives any payment
or distribution of assets of the Company of any kind with respect to the
Debentures in contravention of any terms contained in this Indenture, whether in
cash, property or securities, including, without limitation, by way of set-off
or otherwise, then such payment or distribution shall be held by the recipient
in trust for the benefit of holders of Senior Debt, and shall be immediately
paid over and delivered to the holders of Senior Debt or their
representative(s), to the extent necessary to make payment in full in cash or
other consideration satisfactory to such holders of all Senior Debt remaining

                                       84
<Page>

unpaid, after giving effect to any concurrent payment or distribution or
provision therefor, to or for the holders of Senior Debt; provided, that the
foregoing shall apply to the Trustee only if a Trust Officer has actual
knowledge (as determined in accordance with Section 17.11) that such payment or
distribution is prohibited by this Indenture.

          With respect to the holders of Senior Debt, the Trustee undertakes to
perform only such obligations on the part of the Trustee as are specifically set
forth in this Article 17, and no implied covenants or obligations with respect
to the holders of Senior Debt shall be read into this Indenture against the
Trustee. The Trustee shall not be deemed to owe any fiduciary duty to the
holders of Senior Debt, and shall not be liable to any such holders if the
Trustee shall pay over or distribute to or on behalf of holders of Debentures or
the Company or any other person money or assets to which any holders of Senior
Debt shall be entitled by virtue of this Article 17, except if such payment or
distribution is made as a result of the willful misconduct of the Trustee in
breach of the express terms of this Article 17 applicable to the Trustee.

          SECTION 17.06. NOTICE BY COMPANY. The Company shall promptly notify
the Trustee of any facts known to the Company that would cause a payment of any
obligations with respect to the Debentures or the purchase of any Debentures by
the Company to violate this Article 17, but failure to give such notice shall
not affect the subordination of the Debentures to the Senior Debt as provided in
this Article 17.

          SECTION 17.07. SUBROGATION. After all Senior Debt is paid in full and
until the Debentures are paid in full, holders of Debentures shall be subrogated
(equally and ratably with all other indebtedness pari passu with the Debentures)
to the rights of holders of Senior Debt to receive distributions applicable to
Senior Debt to the extent that distributions otherwise payable to the holders of
Debentures have been applied to the payment of Senior Debt. A distribution made
under this Article 17 to holders of Senior Debt that otherwise would have been
made to holders of Debentures is not, as between the Company and holders of
Debentures, a payment by the Company on the Debentures.

          SECTION 17.08. RELATIVE RIGHTS. This Article 17 defines the relative
rights of holders of Debentures and holders of Senior Debt. Nothing contained in
this Indenture shall otherwise:

          (a)    impair, as between the Company and holders of Debentures, the
     obligation of the Company, which is absolute and unconditional, to pay
     principal of or premium, if any, and interest (including Contingent
     Interest and Additional Interest, if any) on the Debentures in accordance
     with their terms;

          (b)    affect the relative rights of holders of Debentures and
     creditors (other than with respect to Senior Debt) of the Company, other
     than their rights in relation to holders of Senior Debt; or

          (c)    prevent the Trustee or any holder of Debentures from exercising
     its available remedies upon a Default or Event of Default, subject to the
     notice requirements of Section 6.01 and to the rights of holders and owners
     of Senior Debt to receive distributions and payments otherwise payable to
     holders of Debentures.

                                       85
<Page>

          If the Company fails because of this Article 17 to pay principal of,
premium, if any, or interest (including Contingent Interest and Additional
Interest, if any) on a Debenture on the due date, the failure is still a Default
or Event of Default.

          SECTION 17.09. SUBORDINATION MAY NOT BE IMPAIRED BY COMPANY. No right
of any holder of Senior Debt to enforce the subordination of the indebtedness
evidenced by the Debentures shall be impaired by any act or failure to act by
the Company or any holder of Debentures or by the failure of the Company or any
such holder to comply with this Indenture.

          SECTION 17.10. DISTRIBUTION OR NOTICE TO REPRESENTATIVE. Whenever a
distribution is to be made or a notice given to holders of Senior Debt, the
distribution may be made and the notice given to their representative(s).

          Upon any payment or distribution of assets of the Company referred to
in this Article 17, the Trustee and the holders of Debentures shall be entitled
to rely upon any order or decree made by any court of competent jurisdiction or
upon any certificate or instruction of any such representative of any holder of
Senior Debt or of the liquidating trustee or agent or other person making any
distribution to the Trustee or to the holders of Debentures for the purpose of
ascertaining the persons entitled to participate in such distribution, the
holders of the Senior Debt and other indebtedness of the Company, the amount
thereof or payable thereon, the amount or amounts paid or distributed thereon
and all other facts pertinent thereto or to this Article 17.

          In the event that the Trustee determines, in good faith, that evidence
is required with respect to the right of any Person as a holder of Senior Debt
to participate in any payment or distribution pursuant to this Article 17, the
Trustee may (but shall not be obligated to) request such Person to furnish
evidence to the reasonable satisfaction of the Trustee as to the amount of the
Senior Debt held by such Person, the extent to which such Person is entitled to
participate in such payment or distribution and other facts pertinent to the
rights of such Person under this Article 17. If such evidence is not furnished,
the Trustee may defer any payment to such Person pending judicial determination
as to the right of such Person to receive such payment. The provisions of
Section 7.02 shall be applicable to all actions or omissions of the Trustee
pursuant to this Article 17.

          SECTION 17.11. RIGHTS OF TRUSTEE AND PAYING AGENT. The Company shall
give prompt written notice to the Trustee of any fact known to the Company that
would prohibit the making of any payment to or by the Trustee in respect of the
Debentures. Notwithstanding the provisions of this Article 17 or any other
provision of this Indenture, the Trustee shall not be charged with knowledge of
the existence of any facts that would prohibit the making of any payment or
distribution by the Trustee (other than pursuant to Section 17.4), and the
Trustee may continue to make payments on the Debentures, unless a Trust Officer
shall have received at least two (2) Business Days prior to the date of such
payment or distribution written notice of facts that would cause such payment or
distribution with respect to the Debentures to violate this Article e17. Only
the Company or the holder or representative of any class of Senior Debt may give
such notice.

          Nothing contained in this Article 17 shall apply to or impair the
claims of, or payments to, the Trustee under or pursuant to Section 7.06.

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<Page>

          The Trustee in its individual or any other capacity may hold Senior
Debt with the same rights it would have if it were not Trustee.

          SECTION 17.12. AUTHORIZATION TO EFFECT SUBORDINATION. Each holder of a
Debenture by such holder's acceptance thereof authorizes and directs the Trustee
on the holder's behalf to take such action as may be necessary or appropriate to
effectuate the subordination as provided in this Article 17, and appoints the
Trustee to act as the holder's attorney-in-fact for any and all such purposes.
If the Trustee does not file a proper proof of claim or proof of debt in the
form required in any proceeding referred to in Section 6.02 at least thirty (30)
days before the expiration of the time to file such claim, the holders of any
Senior Debt or their representatives are hereby authorized to file an
appropriate claim for and on behalf of the holders of the Debentures.

          SECTION 17.13. ARTICLE APPLICABLE TO PAYING AGENTS. In case at any
time any Paying Agent other than the Trustee shall have been appointed by the
Company and be then acting hereunder, the term "Trustee" as used in this Article
shall in such case (unless the context otherwise requires) be construed as
extending to and including such Paying Agent within its meaning as fully for all
intents and purposes as if such Paying Agent were named in this Article in
addition to or in place of the Trustee.

          SECTION 17.14. SENIOR DEBT ENTITLED TO RELY. Each holder by accepting
a Debenture acknowledges and agrees that the foregoing subordination provisions
are, and are intended to be, an inducement and a consideration to each holder of
Senior Debt, whether such Senior Debt was created or acquired before or after
the issuance of the Securities, to acquire and continue to hold, or to continue
to hold, such Senior Debt and such holder of Senior Debt shall be deemed
conclusively to have relied on such subordination provisions in acquiring and
continuing to hold, or in continuing to hold, such Senior Debt.

          SECTION 17.15. PERMITTED PAYMENTS. Notwithstanding anything to the
contrary contained in this Article 17, the holders of Debentures may receive and
retain at any time on or prior to the Stated Maturity (i) securities that are
subordinated to at least the same extent as the Debentures to (a) Senior Debt
and (b) any securities issued in exchange for Senior Debt and (ii) payments and
other distributions made from any trust created pursuant to Section 12.01.

          SECTION 17.16. NO WAIVER OF SUBORDINATION PROVISIONS. No right of any
present or future holder of any Senior Debt to enforce subordination as herein
provided shall at any time in any way be prejudiced or impaired by any act or
failure to act on the part of the Company, or by any non-compliance by the
Company with the terms, provisions and covenants of this Indenture, regardless
of any knowledge thereof any such holder may have or be otherwise charged with.

          Without in any way limiting the generality of the foregoing paragraph,
the holders of Senior Debt may, at any time and from time to time, without the
consent of or notice to the Trustee or the holders of the Debentures, without
incurring responsibility to the holders of the Debentures and without impairing
or releasing the subordination provided in this Article 17 or the obligations
hereunder of the holders of the Debentures to the holders of Senior Debt, do any
one or more of the following, subject to any rights of the Company in respect
thereof: (i) change

                                       87
<Page>

the manner, place or terms of payment or extend the time of payment of, or renew
or alter, Senior Debt, or otherwise amend or supplement in any manner Senior
Debt or any instrument evidencing the same or any agreement under which Senior
Debt is outstanding; (ii) sell, exchange, release or otherwise deal with any
property pledged, mortgaged or otherwise securing Senior Debt; (iii) release any
person liable in any manner for the collection of Senior Debt; and (iv) exercise
or refrain from exercising any rights against the Company and any other person.

            [THE REMAINDER OF THIS PAGE IS INTENTIONALLY LEFT BLANK]

                                       88
<Page>

          IN WITNESS WHEREOF, the parties hereto have caused this Indenture to
be duly executed.

                                 CHARLES RIVER ASSOCIATES INCORPORATED


                                 By:   /s/ James C. Burrows
                                    -------------------------------------------
                                    Name: James C. Burrows
                                    Title: President and Chief Executive Officer

                                 U.S. BANK NATIONAL ASSOCIATION,
                                 as Trustee


                                 By:   /s/ Chi C. Ma
                                    -------------------------------------------
                                    Name: Chi C. Ma
                                    Title: Vice President

<Page>

                                                                      APPENDIX A

                        PROVISIONS RELATING TO DEBENTURES

          1. DEFINITIONS

          1.1 DEFINITIONS

          Except as defined in this Appendix A, terms used in this Appendix A
shall have the meanings indicated in the Indenture to which this Appendix A is
attached. Unless otherwise indicated, references to Sections means Sections of
this Appendix. For the purposes of this Appendix A, the following terms shall
have the meanings indicated below:

          "DEFINITIVE DEBENTURE" means a certificated Debenture (bearing the
Restricted Securities Legend if the transfer of such Debenture is restricted by
applicable law) that does not include the Global Debentures Legend.

          "GLOBAL DEBENTURES LEGEND" means the legend set forth under that
caption in Exhibit A to this Indenture.

          "QIB" means a "qualified institutional buyer" as defined in Rule 144A.

          "RESTRICTED SECURITIES LEGEND" means the legend set forth in Section
2.3(d)(i).

          "SECURITIES CUSTODIAN" means the custodian with respect to a Global
Debenture (as appointed by the Depositary) or any successor Person thereto, who
shall initially be the Trustee.

          "SHELF REGISTRATION STATEMENT" means a registration statement filed by
the Company in connection with an offer and sale of Debentures pursuant to the
Registration Rights Agreement.

          "TRANSFER RESTRICTED DEBENTURES" means Definitive Debentures and any
other Debentures that bear or are required by the terms of this Indenture to
bear the Restricted Securities Legend.

          1.2 OTHER DEFINITIONS

<Table>
<S>                                                             <C>
 "AGENT MEMBERS"............................................... Section 2.1(c)
"GLOBAL DEBENTURE"............................................. Section 2.1(b)
</Table>

                                       A-1
<Page>

          2. THE DEBENTURES

          2.1 FORM AND DATING

          (a) The Debentures will be (i) offered and sold by the Company
pursuant to the Purchase Agreement and (ii) resold, initially only to QIBs in
reliance on Rule 144A. The Debentures may thereafter be transferred to, among
others, QIBs.

          (b) GLOBAL DEBENTURES. Debentures shall be issued initially in the
form of one or more permanent global Debentures in definitive, fully registered
form (collectively, the "GLOBAL DEBENTURE"), without interest coupons and
bearing the Global Debentures Legend and Restricted Securities Legend, which
shall be deposited on behalf of the purchasers of the Debentures represented
thereby with the Securities Custodian and registered in the name of the
Depositary or a nominee of the Depositary, duly executed by the Company and
authenticated by the Trustee as provided in this Indenture. The aggregate
principal amount of the Global Debentures may from time to time be increased or
decreased by adjustments made on the records of the Trustee and the Depositary
or its nominee and on the schedules thereto as hereinafter provided.

          (c) BOOK-ENTRY PROVISIONS. This Section 2.1(c) shall apply only to a
Global Debenture deposited with or on behalf of the Depositary.

          The Company shall execute and the Trustee shall, in accordance with
this Section 2.1(c) and Section 2.2 and pursuant to an order of the Company
signed by two Officers, authenticate and deliver one or more Global Debentures
that (i) shall be registered in the name of the Depositary for such Global
Debenture or Global Debentures or the nominee of the Depositary and (ii) shall
be delivered by the Trustee to the Depositary or pursuant to the Depositary's
instructions or held by the Trustee as Securities Custodian.

          Members of, or participants in, the Depositary ("AGENT MEMBERS") shall
have no rights under this Indenture with respect to any Global Debenture held on
their behalf by the Depositary or by the Trustee as Securities Custodian or
under such Global Debenture, and the Depositary may be treated by the Company,
the Trustee and any agent of the Company or the Trustee as the absolute owner of
such Global Debenture for all purposes whatsoever. Notwithstanding the
foregoing, nothing herein shall prevent the Company, the Trustee or any agent of
the Company or the Trustee from giving effect to any written certification,
proxy or other authorization furnished by the Depositary (or, if registered in
the name thereof, its nominee) or impair, as between the Depositary and its
Agent Members, the operation of customary practices of the Depositary governing
the exercise of the rights of a holder of a beneficial interest in any Global
Debenture.

          (d) DEFINITIVE DEBENTURES. Except as provided in Section 2.3 or 2.4,
owners of beneficial interests in Global Debentures will not be entitled to
receive physical delivery of certificated Debentures.

          2.2 AUTHENTICATION. The Trustee shall authenticate and make available
for delivery upon a written order of the Company signed by two Officers
Debentures for original issue on the date hereof in an aggregate principal
amount of up to $75,000,000 (or up to

                                       A-2
<Page>

$90,000,000 if the Initial Purchasers' option to purchase additional Debentures
set forth in the Purchase Agreement is exercised in full).

          2.3 TRANSFER AND EXCHANGE. (a) TRANSFER AND EXCHANGE OF DEFINITIVE
DEBENTURES. When Definitive Debentures are presented to the Debenture Registrar
with a request:

          (i) to register the transfer of such Definitive Debentures; or

          (ii) to exchange such Definitive Debentures for an equal principal
     amount of Definitive Debentures of other authorized denominations,

the Debenture Registrar shall register the transfer or make the exchange as
requested if its reasonable requirements for such transaction are met; PROVIDED,
HOWEVER, that the Definitive Debentures surrendered for transfer or exchange:

          (1) shall be duly endorsed or accompanied by a written instrument of
     transfer in form reasonably satisfactory to the Company and the Debenture
     Registrar, duly executed by the holder thereof or its attorney duly
     authorized in writing; and

          (2) in the case of Transfer Restricted Debentures, are accompanied by
     the following additional information and documents, as applicable:

                 (A) if such Definitive Debentures are being delivered to the
          Debenture Registrar by a holder for registration in the name of such
          holder, without transfer, a certification from such holder to that
          effect (in the form set forth on the reverse side of the Debenture);
          or

                 (B) if such Definitive Debentures are being transferred to the
          Company, a certification to that effect (in the form set forth on the
          reverse side of the Debenture); or

                 (C) if such Definitive Debentures are being transferred
          pursuant to an exemption from registration in accordance with Rule 144
          under the Securities Act or in reliance upon another exemption from
          the registration requirements of the Securities Act, (x) a
          certification to that effect (in the form set forth on the reverse
          side of the Debenture) and (y) if the Company so requests, an opinion
          of counsel or other evidence reasonably satisfactory to it as to the
          compliance with the restrictions set forth in the legend set forth in
          Section 2.3(d)(i).

          (b) RESTRICTIONS ON TRANSFER OF A DEFINITIVE DEBENTURE FOR A
BENEFICIAL INTEREST IN A GLOBAL DEBENTURE. A Definitive Debenture may not be
exchanged for a beneficial interest in a Global Debenture except upon
satisfaction of the requirements set forth below. Upon receipt by the Trustee of
a Definitive Debenture, duly endorsed or accompanied by a written instrument of
transfer in form reasonably satisfactory to the Company and the Debenture
Registrar, together with:

                                       A-3
<Page>

          (i) certification (in the form set forth on the reverse side of the
     Debenture) that such Definitive Debenture is being transferred to a QIB in
     accordance with Rule 144A; and

          (ii) written instructions directing the Trustee to make, or to direct
     the Securities Custodian to make, an adjustment on its books and records
     with respect to such Global Debenture to reflect an increase in the
     aggregate principal amount of the Debentures represented by the Global
     Debenture, such instructions to contain information regarding the
     Depositary account to be credited with such increase, then the Trustee
     shall cancel such Definitive Debenture and cause, or direct the Securities
     Custodian to cause, in accordance with the standing instructions and
     procedures existing between the Depositary and the Securities Custodian,
     the aggregate principal amount of Debentures represented by the Global
     Debenture to be increased by the aggregate principal amount of the
     Definitive Debenture to be exchanged and shall credit or cause to be
     credited to the account of the Person specified in such instructions a
     beneficial interest in the Global Debenture equal to the principal amount
     of the Definitive Debenture so canceled. If no Global Debentures are then
     outstanding and the Global Debenture has not been previously exchanged for
     Definitive Debentures pursuant to Section 2.4, the Company shall issue and
     the Trustee shall authenticate, upon written order of the Company in the
     form of an Officers' Certificate, a new Global Debenture in the appropriate
     principal amount.

          (c) TRANSFER AND EXCHANGE OF GLOBAL DEBENTURES. (i) The transfer and
exchange of Global Debentures or beneficial interests therein shall be effected
through the Depositary, in accordance with this Indenture (including applicable
restrictions on transfer set forth herein, if any) and the procedures of the
Depositary therefor. A transferor of a beneficial interest in a Global Debenture
shall deliver a written order given in accordance with the Depositary's
procedures containing information regarding the participant account of the
Depositary to be credited with a beneficial interest in such Global Debenture or
another Global Debenture and such account shall be credited in accordance with
such order with a beneficial interest in the applicable Global Debenture and the
account of the Person making the transfer shall be debited by an amount equal to
the beneficial interest in the Global Debenture being transferred.

          (ii) If the proposed transfer is a transfer of a beneficial interest
     in one Global Debenture to a beneficial interest in another Global
     Debenture, the Debenture Registrar shall reflect on its books and records
     the date and an increase in the principal amount of the Global Debenture to
     which such interest is being transferred in an amount equal to the
     principal amount of the interest to be so transferred, and the Debenture
     Registrar shall reflect on its books and records the date and a
     corresponding decrease in the principal amount of Global Debenture from
     which such interest is being transferred.

          (iii) Notwithstanding any other provisions of this Appendix (other
     than the provisions set forth in Section 2.4), a Global Debenture may not
     be transferred as a whole except by the Depositary to a nominee of the
     Depositary or by a nominee of the Depositary to the Depositary or another
     nominee of the Depositary or by the Depositary or any such nominee to a
     successor Depositary or a nominee of such successor Depositary.

                                       A-4
<Page>

          (iv) In the event that a Global Debenture is exchanged for Definitive
     Debentures pursuant to Section 2.4 prior to the effectiveness of a Shelf
     Registration Statement with respect to such Definitive Debentures, such
     Definitive Debentures may be exchanged only in accordance with such
     procedures as are substantially consistent with the provisions of this
     Section 2.3 (including the certification requirements set forth on the
     reverse of the Initial Debentures intended to ensure that such transfers
     comply with Rule 144A or such other applicable exemption from registration
     under the Securities Act, as the case may be) and such other procedures as
     may from time to time be adopted by the Company.

          (d) LEGEND.

          (i) Except as permitted by the following paragraphs (ii) and (iii),
     each Debenture certificate evidencing the Global Debentures and the
     Definitive Debentures (and all Debentures issued in exchange therefor or in
     substitution thereof) shall bear a legend in substantially the following
     form (each defined term in the legend being defined as such for purposes of
     the legend only):

     "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
     AMENDED (THE "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY STATE OR
     OTHER JURISDICTION. NEITHER THIS SECURITY NOR ANY INTEREST OR PARTICIPATION
     HEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED
     OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH
     TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, SUCH REGISTRATION. THE
     HOLDER OF THIS SECURITY BY ITS ACCEPTANCE HEREOF (1) REPRESENTS THAT IT IS
     A "QUALIFIED INSTITUTIONAL BUYER" (AS DEFINED IN RULE 144A UNDER THE
     SECURITIES ACT ("Rule 144A")); (2) AGREES ON ITS OWN BEHALF AND ON BEHALF
     OF ANY INVESTOR ACCOUNT FOR WHICH IT HAS PURCHASED SECURITIES, TO OFFER,
     SELL OR OTHERWISE TRANSFER SUCH SECURITY, PRIOR TO THE EXPIRATION OF THE
     HOLDING PERIOD APPLICABLE TO SALES OF THIS SECURITY UNDER RULE 144(k) UNDER
     THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION), ONLY (A) TO CHARLES RIVER
     ASSOCIATES INCORPORATED (THE "ISSUER"), (B) PURSUANT TO A REGISTRATION
     STATEMENT THAT HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT (AND
     WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER), (C) FOR SO
     LONG AS THE SECURITIES ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A, IN
     COMPLIANCE WITH RULE 144A TO A PERSON IT REASONABLY BELIEVES IS A QUALIFIED
     INSTITUTIONAL BUYER THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT
     OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE
     TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A OR (D) PURSUANT TO ANOTHER
     AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES
     ACT, SUBJECT TO THE ISSUER'S AND THE TRUSTEE'S RIGHT PRIOR TO ANY SUCH
     OFFER, SALE OR TRANSFER PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY OF
     AN OPINION OF

                                       A-5
<Page>

     COUNSEL, CERTIFICATION AND/ OR OTHER INFORMATION SATISFACTORY TO EACH OF
     THEM; AND (3) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THIS
     SECURITY IS TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS
     LEGEND. THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF
     THIS SECURITY PURSUANT TO CLAUSE 2(B) ABOVE OR UPON ANY TRANSFER OF THIS
     SECURITY UNDER RULE 144 UNDER THE SECURITIES ACT (OR ANY SUCCESSOR
     PROVISION)."

          Each Definitive Debenture shall bear the following additional legend:

     "IN CONNECTION WITH ANY TRANSFER, THE HOLDER WILL DELIVER TO THE REGISTRAR
     AND TRANSFER AGENT SUCH CERTIFICATES AND OTHER INFORMATION AS SUCH TRANSFER
     AGENT MAY REASONABLY REQUIRE TO CONFIRM THAT THE TRANSFER COMPLIES WITH THE
     FOREGOING RESTRICTIONS."

          Until the expiration of the holding period applicable to sales thereof
     under Rule 144(k) under the Securities Act (or any successor provision),
     any stock certificate representing Common Stock issued upon conversion of
     any Debenture shall bear a legend in substantially the following form,
     unless such Common Stock has been sold pursuant to a registration statement
     that has been declared effective under the Securities Act (and which
     continues to be effective at the time of such transfer) or pursuant to Rule
     144 under the Securities Act or any similar provision then in force, or
     such Common Stock has been issued upon conversion of Debentures that have
     been transferred pursuant to a registration statement that has been
     declared effective under the Securities Act or pursuant to Rule 144 under
     the Securities Act or any similar provision then in force, or unless
     otherwise agreed by the Company in writing with written notice thereof to
     the transfer agent:

     "THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
     AMENDED (THE "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY STATE OR
     OTHER JURISDICTION. NEITHER THIS SECURITY NOR ANY INTEREST OR PARTICIPATION
     HEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED
     OR OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH
     TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, SUCH REGISTRATION. THE
     HOLDER OF THIS SECURITY, BY ITS ACCEPTANCE HEREOF, (1) REPRESENTS THAT IT
     IS A "QUALIFIED INSTITUTIONAL BUYER" (AS DEFINED IN RULE 144A UNDER THE
     SECURITIES ACT ("RULE 144A")); (2) AGREES ON ITS OWN BEHALF AND ON BEHALF
     OF ANY INVESTOR ACCOUNT FOR WHICH IT HAS PURCHASED SECURITIES, TO OFFER,
     SELL OR OTHERWISE TRANSFER SUCH SECURITY, PRIOR TO THE EXPIRATION OF THE
     HOLDING PERIOD APPLICABLE TO SALES OF THIS SECURITY UNDER RULE 144(k) UNDER
     THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION), ONLY (A) TO CHARLES RIVER
     ASSOCIATES INCORPORATED (THE "ISSUER"), (B) PURSUANT TO A REGISTRATION

                                       A-6
<Page>

     STATEMENT THAT HAS BEEN DECLARED EFFECTIVE UNDER THE SECURITIES ACT (AND
     WHICH CONTINUES TO BE EFFECTIVE AT THE TIME OF SUCH TRANSFER), (C) FOR SO
     LONG AS THE SECURITIES ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A, IN
     COMPLIANCE WITH RULE 144A TO A PERSON IT REASONABLY BELIEVES IS A QUALIFIED
     INSTITUTIONAL BUYER THAT PURCHASES FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT
     OF A QUALIFIED INSTITUTIONAL BUYER TO WHOM NOTICE IS GIVEN THAT THE
     TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A OR (D) PURSUANT TO ANOTHER
     AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS OF THE SECURITIES
     ACT, SUBJECT TO THE ISSUER'S AND THE TRUSTEE'S RIGHT PRIOR TO ANY SUCH
     OFFER, SALE OR TRANSFER PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY OF
     AN OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY
     TO EACH OF THEM; AND (3) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM
     THIS SECURITY IS TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS
     LEGEND. THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF
     THIS SECURITY PURSUANT TO CLAUSE 2(B) ABOVE OR UPON ANY TRANSFER OF THIS
     SECURITY UNDER RULE 144 UNDER THE SECURITIES ACT (OR ANY SUCCESSOR
     PROVISION)."

          (ii) Upon any sale or transfer of a Transfer Restricted Debenture that
     is a Definitive Debenture, the Debenture Registrar shall permit the holder
     thereof to exchange such Transfer Restricted Debenture for a Definitive
     Debenture that does not bear the legends set forth above and rescind any
     restriction on the transfer of such Transfer Restricted Debenture if the
     holder certifies in writing to the Debenture Registrar that its request for
     such exchange was made in reliance on Rule 144 (such certification to be in
     the form set forth on the reverse of the Debenture).

          (iii) After a transfer of any Debentures during the period of the
     effectiveness of a Shelf Registration Statement with respect to such
     Debentures pursuant to the terms of such Shelf Registration Statement, all
     requirements pertaining to the Restricted Securities Legend on such
     Debentures shall cease to apply and the requirements that any such
     Debentures be issued in global form shall continue to apply.

          (iv) Each Debenture certificate evidencing the Global Debentures and
     the Definitive Debentures (and all Debentures issued in exchange therefor
     or in substitution thereof) shall bear an additional legend in
     substantially the following form (each defined term in the legend being
     defined as such for purposes of the legend only).

     "THE ISSUER AGREES, AND BY ACCEPTANCE OF A BENEFICIAL OWNERSHIP INTEREST IN
     THIS SECURITY EACH BENEFICIAL HOLDER OF SUCH SECURITY WILL BE DEEMED TO
     HAVE AGREED, FOR UNITED STATES FEDERAL INCOME TAX PURPOSES (1) TO TREAT THE
     SECURITY AS INDEBTEDNESS OF THE ISSUER THAT IS SUBJECT TO TREAS. REG. SEC.
     1.1275-4 (THE "CONTINGENT PAYMENT REGULATIONS") AND, FOR PURPOSES OF THE
     CONTINGENT PAYMENT REGULATIONS, TO TREAT THE

                                       A-7
<Page>

     FAIR MARKET VALUE OF ANY COMMON STOCK BENEFICIALLY RECEIVED BY A BENEFICIAL
     HOLDER UPON ANY CONVERSION OF THE SECURITY AS A CONTINGENT PAYMENT AND (2)
     TO BE BOUND BY THE ISSUER'S DETERMINATION OF THE "COMPARABLE YIELD" AND THE
     "PROJECTED PAYMENT SCHEDULE" WITHIN THE MEANING OF THE CONTINGENT PAYMENT
     REGULATIONS, WITH RESPECT TO THE SECURITY. A HOLDER OF THIS SECURITY MAY
     OBTAIN THE ISSUE PRICE, AMOUNT OF ORIGINAL ISSUE DISCOUNT, ISSUE DATE,
     YIELD TO MATURITY, COMPARABLE YIELD AND PROJECTED PAYMENT SCHEDULE FOR THE
     SECURITY BY SUBMITTING A WRITTEN REQUEST FOR SUCH INFORMATION TO THE ISSUER
     AT THE FOLLOWING ADDRESS: CHARLES RIVER ASSOCIATES INCORPORATED, 200
     CLARENDON STREET, T-33, BOSTON, MASSACHUSETTS 02116, ATTENTION: CHIEF
     FINANCIAL OFFICER."

          (e) CANCELLATION OR ADJUSTMENT OF GLOBAL DEBENTURE. At such time as
all beneficial interests in a Global Debenture have either been exchanged for
Definitive Debentures, transferred, redeemed, repurchased or canceled, such
Global Debenture shall be returned by the Depositary to the Trustee or retained
by the Trustee. At any time prior to such cancellation, if any beneficial
interest in a Global Debenture is exchanged for Definitive Debentures,
transferred in exchange for an interest in another Global Debenture, redeemed,
repurchased or canceled, the principal amount of Debentures represented by such
Global Debenture shall be reduced and an adjustment shall be made on the books
and records of the Trustee (if it is then the Securities Custodian for such
Global Debenture) with respect to such Global Debenture, by the Trustee or the
Securities Custodian, to reflect such reduction.

          (f) OBLIGATIONS WITH RESPECT TO TRANSFERS AND EXCHANGES OF DEBENTURES.

          (i) To permit registrations of transfers and exchanges, the Company
shall execute, and the Trustee shall authenticate, Definitive Debentures and
Global Debentures at the Debenture Registrar's request.

          (ii) No service charge shall be made for any registration of transfer
or exchange, but the Company may require payment of a sum sufficient to cover
any transfer tax, assessments, or similar governmental charge payable in
connection therewith (other than any such transfer taxes, assessments or similar
governmental charge payable upon exchanges pursuant to Sections 2.07, 3.03 and
10.04 of this Indenture).

          (iii) Prior to the due presentation for registration of transfer of
any Debenture, the Company, the Trustee, the Paying Agent or the Debenture
Registrar may deem and treat the Person in whose name a Debenture is registered
as the absolute owner of such Debenture for the purpose of receiving payment of
principal of and interest on such Debenture and for all other purposes
whatsoever, whether or not such Debenture is overdue, and none of the Company,
the Trustee, the Paying Agent or the Debenture Registrar shall be affected by
notice to the contrary.

          (iv) All Debentures issued upon any transfer or exchange pursuant to
the terms of this Indenture shall evidence the same debt and shall be entitled
to the same benefits under this Indenture as the Debentures surrendered upon
such transfer or exchange.

                                       A-8
<Page>

          (g) NO OBLIGATION OF THE TRUSTEE.

          (i) The Trustee shall have no responsibility or obligation to any
beneficial owner of a Global Debenture, a member of, or a participant in, the
Depositary or any other Person with respect to the accuracy of the records of
the Depositary or its nominee or of any participant or member thereof, with
respect to any ownership interest in the Debentures or with respect to the
delivery to any participant, member, beneficial owner or other Person (other
than the Depositary) of any notice (including any notice of redemption or
repurchase) or the payment of any amount, under or with respect to the
Debentures. All notices and communications to be given to the holders and all
payments to be made to holders under the Debentures shall be given or made only
to the registered holders (which shall be the Depositary or its nominee in the
case of a Global Debenture). The rights of beneficial owners in any Global
Debenture shall be exercised only through the Depositary subject to the
applicable rules and procedures of the Depositary. The Trustee may rely and
shall be fully protected in relying upon information furnished by the Depositary
with respect to its members, participants and any beneficial owners.

          (ii) The Trustee shall have no obligation or duty to monitor,
determine or inquire as to compliance with any restrictions on transfer imposed
under this Indenture or under applicable law with respect to any transfer of any
interest in any Debenture (including any transfers between or among Depositary
participants, members or beneficial owners in any Global Debenture) other than
to require delivery of such certificates and other documentation or evidence as
are expressly required by, and to do so if and when expressly required by, the
terms of this Indenture, and to examine the same to determine substantial
compliance as to form with the express requirements hereof.

          2.4 DEFINITIVE DEBENTURES

          (a) A Global Debenture deposited with the Depositary or with the
Trustee as Securities Custodian pursuant to Section 2.1 shall be transferred to
the beneficial owners thereof in the form of Definitive Debentures in an
aggregate principal amount equal to the principal amount of such Global
Debenture, in exchange for such Global Debenture, only if such transfer complies
with Section 2.3 and (i) the Depositary notifies the Company that it is
unwilling or unable to continue as a depositary for such Global Debenture or if
at any time the Depositary ceases to be a "clearing agency" registered under the
Exchange Act, and a successor depositary is not appointed by the Company within
90 days of such notice or after the Company becomes aware of such cessation,
(ii) an Event of Default has occurred and is continuing or (iii) the Company, in
its sole discretion, notifies the Trustee in writing that it elects to cause the
issuance of Definitive Debentures under this Indenture.

          (b) Any Global Debenture that is transferable to the beneficial owners
thereof pursuant to this Section 2.4 shall be surrendered by the Depositary to
the Trustee, to be so transferred, in whole or from time to time in part,
without charge, and the Trustee shall authenticate and deliver, upon such
transfer of each portion of such Global Debenture, an equal aggregate principal
amount of Definitive Debentures of authorized denominations. Any portion of a
Global Debenture transferred pursuant to this Section shall be executed,
authenticated and delivered only in denominations of $1,000 principal amount and
any integral multiple thereof and registered in such names as the Depositary
shall direct. Any certificated Debenture in the

                                       A-9
<Page>

form of a Definitive Debenture delivered in exchange for an interest in the
Global Debenture shall, except as otherwise provided by Section 2.3(d), bear the
Restricted Securities Legend.

          (c) Subject to the provisions of Section 2.4(b), the registered holder
of a Global Debenture may grant proxies and otherwise authorize any Person,
including Agent Members and Persons that may hold interests through Agent
Members, to take any action which a holder is entitled to take under this
Indenture or the Debentures.

          (d) In the event of the occurrence of any of the events specified in
Section 2.4(a)(i), (ii) or (iii), the Company will promptly make available to
the Trustee a reasonable supply of Definitive Debentures in fully registered
form without interest coupons.

                                      A-10
<Page>

                                                                       EXHIBIT A

                           [FORM OF FACE OF DEBENTURE]

                           [Global Debentures Legend]

          UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE
OF THE DEPOSITORY TRUST COMPANY, A NEW YORK CORPORATION ("DTC"), NEW YORK, NEW
YORK, TO THE COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR
PAYMENT, AND ANY CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR
SUCH OTHER NAME AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF DTC (AND ANY
PAYMENT IS MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN
AUTHORIZED REPRESENTATIVE OF DTC), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

          TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN
WHOLE, BUT NOT IN PART, TO DTC, TO NOMINEES OF DTC OR TO A SUCCESSOR THEREOF OR
SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL SECURITY SHALL
BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS SET FORTH IN
THE INDENTURE REFERRED TO ON THE REVERSE HEREOF.

                         [Restricted Securities Legend]

          THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
1933, AS AMENDED (THE "SECURITIES ACT"), OR THE SECURITIES LAWS OF ANY STATE OR
OTHER JURISDICTION. NEITHER THIS SECURITY NOR ANY INTEREST OR PARTICIPATION
HEREIN MAY BE REOFFERED, SOLD, ASSIGNED, TRANSFERRED, PLEDGED, ENCUMBERED OR
OTHERWISE DISPOSED OF IN THE ABSENCE OF SUCH REGISTRATION OR UNLESS SUCH
TRANSACTION IS EXEMPT FROM, OR NOT SUBJECT TO, SUCH REGISTRATION. THE HOLDER OF
THIS SECURITY, BY ITS ACCEPTANCE HEREOF, (1) REPRESENTS THAT IT IS A "QUALIFIED
INSTITUTIONAL BUYER" (AS DEFINED IN RULE 144A UNDER THE SECURITIES ACT ("RULE
144A")); (2) AGREES ON ITS OWN BEHALF AND ON BEHALF OF ANY INVESTOR ACCOUNT FOR
WHICH IT HAS PURCHASED SECURITIES, TO OFFER, SELL OR OTHERWISE TRANSFER SUCH
SECURITY, PRIOR TO THE EXPIRATION OF THE HOLDING PERIOD APPLICABLE TO SALES OF
THIS SECURITY UNDER RULE 144(k) UNDER THE SECURITIES ACT (OR ANY SUCCESSOR
PROVISION), ONLY (A) TO CHARLES RIVER ASSOCIATES INCORPORATED (THE "ISSUER"),
(B) PURSUANT TO A REGISTRATION STATEMENT THAT HAS BEEN DECLARED EFFECTIVE UNDER
THE SECURITIES ACT (AND WHICH CONTINUES TO

                                       E-1
<Page>

BE EFFECTIVE AT THE TIME OF SUCH TRANSFER), (C) FOR SO LONG AS THE SECURITIES
ARE ELIGIBLE FOR RESALE PURSUANT TO RULE 144A, IN COMPLIANCE WITH RULE 144A TO A
PERSON IT REASONABLY BELIEVES IS A QUALIFIED INSTITUTIONAL BUYER THAT PURCHASES
FOR ITS OWN ACCOUNT OR FOR THE ACCOUNT OF A QUALIFIED INSTITUTIONAL BUYER TO
WHOM NOTICE IS GIVEN THAT THE TRANSFER IS BEING MADE IN RELIANCE ON RULE 144A OR
(D) PURSUANT TO ANOTHER AVAILABLE EXEMPTION FROM THE REGISTRATION REQUIREMENTS
OF THE SECURITIES ACT, SUBJECT TO THE ISSUER'S AND THE TRUSTEE'S RIGHT PRIOR TO
ANY SUCH OFFER, SALE OR TRANSFER PURSUANT TO CLAUSE (D) TO REQUIRE THE DELIVERY
OF AN OPINION OF COUNSEL, CERTIFICATION AND/OR OTHER INFORMATION SATISFACTORY TO
EACH OF THEM; AND (3) AGREES THAT IT WILL DELIVER TO EACH PERSON TO WHOM THIS
SECURITY IS TRANSFERRED A NOTICE SUBSTANTIALLY TO THE EFFECT OF THIS LEGEND.
THIS LEGEND WILL BE REMOVED UPON THE EARLIER OF THE TRANSFER OF THIS SECURITY
PURSUANT TO CLAUSE 2(B) ABOVE OR UPON ANY TRANSFER OF THIS SECURITY UNDER RULE
144 UNDER THE SECURITIES ACT (OR ANY SUCCESSOR PROVISION).

[Each Definitive Debenture shall bear the following additional legend:]

          IN CONNECTION WITH ANY TRANSFER, THE HOLDER WILL DELIVER TO THE
REGISTRAR AND TRANSFER AGENT SUCH CERTIFICATES AND OTHER INFORMATION AS SUCH
TRANSFER AGENT MAY REASONABLY REQUIRE TO CONFIRM THAT THE TRANSFER COMPLIES WITH
THE FOREGOING RESTRICTIONS.

[Each Debenture shall bear the following additional legend:]

          THE ISSUER AGREES, AND BY ACCEPTANCE OF A BENEFICIAL OWNERSHIP
INTEREST IN THIS SECURITY EACH BENEFICIAL HOLDER OF SUCH SECURITY WILL BE DEEMED
TO HAVE AGREED, FOR UNITED STATES FEDERAL INCOME TAX PURPOSES (1) TO TREAT THE
SECURITY AS INDEBTEDNESS OF THE ISSUER THAT IS SUBJECT TO TREAS. REG. SEC.
1.1275-4 (THE "CONTINGENT PAYMENT REGULATIONS") AND, FOR PURPOSES OF THE
CONTINGENT PAYMENT REGULATIONS, TO TREAT THE FAIR MARKET VALUE OF ANY COMMON
STOCK BENEFICIALLY RECEIVED BY A BENEFICIAL HOLDER UPON ANY CONVERSION OF THE
SECURITY AS A CONTINGENT PAYMENT AND (2) TO BE BOUND BY THE ISSUER'S
DETERMINATION OF THE "COMPARABLE YIELD" AND THE "PROJECTED PAYMENT SCHEDULE"
WITHIN THE MEANING OF THE CONTINGENT PAYMENT REGULATIONS, WITH RESPECT TO THE
SECURITY. A HOLDER OF THIS SECURITY MAY OBTAIN THE ISSUE PRICE, AMOUNT OF
ORIGINAL ISSUE DISCOUNT, ISSUE DATE, YIELD TO MATURITY, COMPARABLE YIELD AND
PROJECTED PAYMENT SCHEDULE FOR THE SECURITY BY SUBMITTING A WRITTEN REQUEST FOR
SUCH INFORMATION TO THE ISSUER AT THE FOLLOWING ADDRESS: CHARLES RIVER
ASSOCIATES INCORPORATED, 200 CLARENDON STREET, T-33, BOSTON, MASSACHUSETTS
02116, ATTENTION: CHIEF FINANCIAL OFFICER.

                                       E-2
<Page>

                      CHARLES RIVER ASSOCIATES INCORPORATED

                    2.875% CONVERTIBLE SUBORDINATED DEBENTURE

                                                                    CUSIP:

No.  $

          Charles River Associate Incorporated, a corporation duly organized and
validly existing under the laws of the Commonwealth of Massachusetts (herein
called the "COMPANY", which term includes any successor corporation under the
Indenture referred to on the reverse hereof), for value received, hereby
promises to pay to CEDE & CO. or its registered assigns [the principal sum of [
] dollars] [the principal sum set forth on Schedule I hereto]1 on June 15, 2034
at the office or agency of the Company maintained for that purpose in accordance
with the terms of the Indenture, in such coin or currency of the United States
of America as at the time of payment shall be legal tender for the payment of
public and private debts, and to pay interest, semiannually on June 15 and
December 15 of each year, commencing December 15, 2004, on said principal sum at
said office or agency, in like coin or currency, at the rate per annum of
2.875%, from the June 15 or December 15, as the case may be, next preceding the
date of this Debenture to which interest has been paid or duly provided for,
unless the date hereof is a date to which interest has been paid or duly
provided for, in which case from the date of this Debenture, or unless no
interest has been paid or duly provided for on this Debenture, in which case
from June 21, 2004 until payment of said principal sum has been made or duly
provided for. Except as otherwise provided in the Indenture, the interest
payable on the Debenture pursuant to the Indenture on any June 15 or December 15
will be paid to the Person entitled thereto as it appears in the Debenture
Register at the close of business on the Regular Record Date, which shall be the
June 1 or December 15 (whether or not a Business Day) next preceding such June
15 or December 15, as provided in the Indenture; PROVIDED that any such interest
not punctually paid or duly provided for shall be payable as provided in the
Indenture.

          The Company promises to pay interest at the rate of 2.875% per annum,
compounded semiannually. The Company shall pay interest on overdue principal at
the rate borne by the Debentures plus 1% per annum, and it shall pay interest on
overdue installments of interest at such higher rate to the extent lawful.

          Interest on the Debentures shall be computed on the basis of a 360 day
year of twelve 30 day months.

          Reference is made to the further provisions of this Debenture set
forth on the reverse hereof, including, without limitation, provisions giving
the holder of this Debenture the right to convert this Debenture into Common
Stock of the Company on the terms and subject to the limitations referred to on
the reverse hereof and as more fully specified in the Indenture. Under the
circumstances described in the Indenture, the Company may fulfill all or part of
its conversion obligation by delivering cash in lieu of shares of Common Stock
or a combination of cash and shares of Common Stock.

----------
(1)  For Global Debentures only.

                                       E-3
<Page>

          This Debenture shall be deemed to be a contract made under the laws of
the State of New York, and for all purposes shall be construed in accordance
with and governed by the laws of the State of New York (including Section 5-1401
of the New York General Obligations Law or any successor to such statute).

          The Company has caused CUSIP numbers to be printed on the Debentures
and has directed the Trustee to use CUSIP numbers in notices of redemption as a
convenience to holders. No representation is made as to the accuracy of such
numbers either as printed on the Debentures or as contained in any notice of
redemption and reliance may be placed only on the other identification numbers
placed thereon.

          Subject to certain limitations imposed by the Trust Indenture Act and
the Indenture, the Trustee under the Indenture, in its individual or any other
capacity, may become the owner or pledgee of Debentures and may otherwise deal
with the Company or its Affiliates with the same rights it would have if it were
not Trustee.

          This Debenture shall not be valid or become obligatory for any purpose
until the certificate of authentication hereon shall have been manually signed
by the Trustee or a duly authorized authenticating agent under the Indenture.

          If and to the extent that any provision of this Debenture limits,
qualifies or conflicts with a provision of the Indenture, such Indenture
provision shall control.

                                       E-4
<Page>

          Additional provisions of this Security are set forth on the other side
of this Security.

          IN WITNESS WHEREOF, the parties have caused this instrument to be duly
executed.

                                    CHARLES RIVER ASSOCIATES
                                    INCORPORATED

                                    By:
                                       ---------------------
                                       Name:
                                       Title:


                                    By:
                                       ---------------------
                                       Name:
                                       Title:


Dated:

     TRUSTEE'S CERTIFICATE OF
          AUTHENTICATION

U.S. BANK NATIONAL ASSOCIATION
     as Trustee, certifies
     that this is one of the
     Securities referred to
     in the Indenture.

By:
   ---------------------------
      Authorized Signatory

                                       E-5
<Page>

                         [FORM OF REVERSE OF DEBENTURE]

                      CHARLES RIVER ASSOCIATES INCORPORATED

                    2.875% CONVERTIBLE SUBORDINATED DEBENTURE

          This Debenture is one of a duly authorized issue of Debentures of the
Company, designated as its 2.875% Convertible Subordinated Debentures (herein
called the "DEBENTURES" or the "SECURITIES"), limited in aggregate principal
amount up to $75,000,000 (or up to $90,000,000 if the Initial Purchasers' option
to purchase additional Debentures set forth in the Purchase Agreement is
exercised in full), issued and to be issued under and pursuant to an Indenture
dated as of June 21, 2004 (herein called the "INDENTURE"), between the Company
and U.S. Bank National Association, as trustee (herein called the "TRUSTEE"), to
which Indenture and all indentures supplemental thereto reference is hereby made
for a description of the rights, limitations of rights, obligations, duties and
immunities thereunder of the Trustee, the Company and the holders of the
Debentures.

          The terms of the Debentures include those stated in the Indenture and
those made part of the Indenture by reference to the Trust Indenture Act of 1939
(15 U.S.C. Sections 77aaa-77bbbb) as in effect on the date of the Indenture (the
"Trust Indenture Act"). Terms defined in the Indenture and not defined herein
have the meanings ascribed thereto in the Indenture. The Debentures are subject
to all such terms, and Debentureholders are referred to the Indenture and the
Trust Indenture Act for a statement of those terms. The Debentures are general
obligations of the Company. In the event of a conflict between the terms of the
Indenture or the Registration Rights Agreement and the terms of the Debentures,
the terms of the Indenture or the Registration Rights Agreement and not the
Debentures shall govern.

          Initially, the Trustee will act as Paying Agent and Debenture
Registrar. The Company may appoint and change any Paying Agent or Debenture
Registrar without notice. The Company or any of its domestically incorporated
Wholly Owned Subsidiaries may act as Paying Agent or Debenture Registrar.

          Under the Indenture, Events of Default include, among other things,
(i) default for 30 days in payment of interest (including Contingent Interest
and Additional Interest, if any) on the Debentures; (ii) default in payment of
principal on the Debentures when the same becomes due at Stated Maturity, upon
declaration of acceleration or otherwise, or failure by the Company to purchase
or redeem Debentures when required; (iii) failure by the Company to deliver
shares, cash or other property on conversion of the Debentures in accordance
with the Indenture; (iv) failure by the Company to comply with other agreements
in the Indenture or the Debentures, in certain cases subject to notice and lapse
of time; (iv) certain accelerations (including failure to pay within any grace
period after final maturity) of other Indebtedness of the Company if the amount
accelerated (or so unpaid) exceeds $10.0 million; (v) certain events of
bankruptcy or insolvency with respect to the Company or any Subsidiary and (vi)
certain judgments or decrees for the payment of money in excess of $10.0
million. In case an Event of Default shall have occurred and be continuing, the
principal of and accrued and unpaid interest (including Additional Interest, if
any) on all Debentures may be declared by either the Trustee or the holders of
not less than 25% in aggregate principal amount of the Debentures then
outstanding,

                                       E-6
<Page>

and upon such declaration shall become, due and payable, in the manner, with the
effect and subject to the conditions provided in the Indenture. Certain events
of bankruptcy or insolvency are Events of Default which will result in the
Debentures being due and payable immediately upon the occurrence of such Events
of Default.

          Debentureholders may not enforce the Indenture or the Debentures
except as provided in the Indenture. The Trustee may refuse to enforce the
Indenture or the Debentures unless it receives indemnity or security reasonably
satisfactory to it. Subject to certain limitations, holders of a majority in
principal amount of the Debentures may direct the Trustee in its exercise of any
trust or power. The Trustee may withhold from Debentureholders notice of any
continuing Default (except a Default in payment of principal or interest
(including Contingent Interest and Additional Interest, if any) on any
Debenture) if it determines that withholding notice is in the interest of the
holders.

          A director, officer, employee or stockholder, as such, of the Company
or the Trustee shall not have any liability for any obligations of the Company
under the Debentures or the Indenture or for any claim based on, in respect of
or by reason of such obligations or their creation. By accepting a Debenture,
each Debentureholder waives and releases all such liability. The waiver and
release are part of the consideration for the issue of the Debentures.

          The Indenture contains provisions permitting the Company and the
Trustee, with the consent of the holders of at least a majority in aggregate
principal amount of the Debentures at the time outstanding, to execute
supplemental indentures adding any provisions to or changing in any manner or
eliminating any of the provisions of the Indenture or of any supplemental
indenture or modifying in any manner the rights of the holders of the
Debentures; PROVIDED that without the consent of each Debentureholder affected
thereby no such supplemental indenture shall (i) extend the Stated Maturity of
any Debenture, or reduce the rate or extend the stated time for payment of
interest (including Contingent Interest and Additional Interest, if any) on any
Debenture, or reduce the principal amount of any Debenture or reduce any amount
payable upon redemption or repurchase of any Debenture, or change the time at
which any Debenture may be redeemed or repurchased, or impair the right of any
Debentureholder to receive payment of principal of and interest (including
Contingent Interest and Additional Interest, if any) on such holder's Debentures
on or after the due dates therefor or to institute suit for the enforcement of
any payment on or with respect to such holder's Debentures, or make the
principal of or interest (including Contingent Interest and Additional Interest,
if any) on any Debenture payable in any coin or currency other than that
provided in the Debentures, or affect the obligation of the Company to redeem
any Debenture on a Redemption Date in a manner adverse to such Debentureholder,
or affect the obligation of the Company to repurchase any Debenture upon a
Fundamental Change in a manner adverse to such Debentureholder, or affect the
obligation of the Company to repurchase any Debenture on a Company Repurchase
Date in a manner adverse to such Debentureholder, or impair the right to convert
the Debentures into shares of Common Stock subject to the terms set forth in the
Indenture, including Section 15.06 thereof, or reduce the number of shares of
Common Stock or other property receivable upon conversion, or modify any of the
provisions of Article 10 or Section 6.07 thereof, except to increase any such
percentage or to provide that certain other provisions of the Indenture cannot
be modified or waived without the consent of the holder of each Debenture so
affected, or change any obligation of the Company to maintain an office or
agency in the places and for the purposes set forth in

                                       E-7
<Page>

Section 4.02 thereof, or reduce the quorum or voting requirements set forth in
Article 9 thereof or (ii) reduce the aforesaid percentage of Debentures, the
holders of which are required to consent to any such supplemental indenture.
Subject to the provisions of the Indenture, the holders of a majority in
aggregate principal amount of the Debentures at the time outstanding may on
behalf of the holders of all of the Debentures waive any past default or Event
of Default under the Indenture and its consequences except (A) a default in the
payment of interest (including Contingent Interest and Additional Interest, if
any) on, or the principal of, the Debentures, (B) a failure by the Company to
convert any Debentures into Common Stock, (C) a default in the payment of the
Redemption Price pursuant to Article 3 of the Indenture, (D) a default in the
payment of the Company Repurchase Price or Fundamental Change Repurchase Price
pursuant to Article 3 of the Indenture or (E) a default in respect of a covenant
or provision of the Indenture which under Article 10 of the Indenture cannot be
modified or amended without the consent of the holders of each or all Debentures
then outstanding or affected thereby. Any such consent or waiver by the holder
of this Debenture (unless revoked as provided in the Indenture) shall be
conclusive and binding upon such holder and upon all future holders and owners
of this Debenture and any Debentures which may be issued in exchange or
substitution hereof, irrespective of whether or not any notation thereof is made
upon this Debenture or such other Debentures.

          No reference herein to the Indenture and no provision of this
Debenture or of the Indenture shall alter or impair the obligations of the
Company, which are absolute and unconditional, to pay the principal of and
interest (including Contingent Interest and Additional Interest, if any) on this
Debenture at the place, at the respective times, at the rate and in the coin or
currency herein prescribed.

          Holders must surrender Debentures to a Paying Agent to collect
principal payments. The Company will pay principal and interest (including
Contingent Interest and Additional Interest, if any) in money of the United
States that at the time of payment is legal tender for payment of public and
private debts. Payments in respect of the Debentures represented by a Global
Debenture (including principal and interest (including Additional Interest, if
any)) will be made by wire transfer of immediately available funds to the
accounts specified by The Depository Trust Company. The Company will make all
payments in respect of a Definitive Debenture (including principal and interest
(including Contingent Interest and Additional Interest, if any)) by mailing a
check to the registered address of each holder thereof; PROVIDED, that payments
on a certificated Debenture will be made by wire transfer to a U.S. dollar
account maintained by the payee with a bank in the United States if such holder
elects payment by wire transfer by giving written notice to the Trustee or the
Paying Agent to such effect designating such account no later than 30 days
immediately preceding the relevant due date for payment (or such other date as
the Trustee may accept in its discretion). The Company may also pay interest
(including Contingent Interest and Additional Interest, if any) by check mailed
to the address of a holder as it appears in the Debenture Register, PROVIDED,
that holders with an aggregate principal amount of Debentures in excess of $2
million, may be paid, at their written election, by wire transfer in immediately
available funds. However, payments to the Depositary will be made by wire
transfer of immediately available funds to the account of Depositary or its
nominee.

                                       E-8
<Page>

          The Debentures are issuable in fully registered form, without coupons,
in denominations of $1,000 principal amount and any multiple of $1,000. At the
office or agency of the Company referred to on the face hereof, and in the
manner and subject to the limitations provided in the Indenture, without payment
of any service charge but with payment of a sum sufficient to cover any tax,
assessment or other governmental charge that may be imposed in connection with
any registration or exchange of Debentures, Debentures may be exchanged for a
like aggregate principal amount of Debentures of any other authorized
denominations. The Debenture Registrar may require a holder, among other things,
to furnish appropriate endorsements or transfer documents and to pay any taxes
and fees required by law or permitted by the Indenture.

          The Company promises to pay interest on the principal amount of this
Debenture at the rate per annum shown above; PROVIDED, that Contingent Interest
will accrue on this Debenture as set forth in the Indenture and if a
Registration Default (as defined in the Registration Rights Agreement) occurs,
Additional Interest will accrue on this Debenture as set forth in the
Registration Rights Agreement. The Company will pay interest semiannually in
arrears on June 15 and December 15 of each year, commencing December 15, 2004.
Interest on the Debentures will accrue from the most recent date to which
interest has been paid or, if no interest has been paid, from June 21, 2004. The
Company will pay interest on the Debentures (except defaulted interest) to the
Persons who are registered holders of Debentures at the close of business on the
June 1 or December 1 next preceding the interest payment date even if Debentures
are canceled after the record date and on or before the interest payment date.

          The Debentures are not redeemable prior to June 20, 2011. At any time
on or after June 20, 2011 and prior to Stated Maturity, the Debentures may be
redeemed at the option of the Company, in whole or in part, in cash, upon
mailing a notice of such redemption not less than thirty (30) days but not more
than sixty (60) days before the Redemption Date to the holders of Debentures at
their last registered addresses, all as provided in the Indenture, at a
Redemption Price equal to 100% of the principal amount of Debentures to be
redeemed plus accrued and unpaid interest (including Contingent Interest and
Additional Interest, if any), if any, to but excluding the Redemption Date;
PROVIDED that if the Redemption Date is on June 15 or December 15, then the
interest payable on such date shall be paid to the holder of record on the
preceding June 1 or December 1, respectively.

          The Debentures will be redeemable in multiples of $1,000 principal
amount.

          The Company may not give notice of any redemption of the Debentures if
a default in the payment of interest (including Contingent Interest and
Additional Interest, if any) on the Debentures has occurred and is continuing.

          The Debentures are not subject to redemption through the operation of
any sinking fund.

          Subject to the terms and conditions of the Indenture, the Company
shall become obligated to repurchase for cash, at the option of the holder, all
or any portion of the Debentures held by such holder if a Fundamental Change
occurs at any time prior to maturity of the Debentures, on a Fundamental Change
Repurchase Date specified by the Company (which shall

                                       E-9
<Page>

be no later than thirty-five (35) Business Days after the occurrence of such
Fundamental Change), at a Fundamental Change Repurchase Price equal to 100% of
the principal amount thereof, plus accrued and unpaid interest (including
Contingent Interest and Additional Interest, if any) to (but excluding) the
Fundamental Change Repurchase Date plus the Make-Whole Premium, if applicable;
PROVIDED that if such Fundamental Change Repurchase Date falls after a record
date and on or prior to the corresponding Interest Payment Date, the interest
payable on such Interest Payment Date shall be paid to the holder of record of
this Debenture on the applicable record date instead of the holders surrendering
such Debentures for repurchase on such date. The Company shall mail to all
holders of record of such Debentures a notice of the occurrence of a Fundamental
Change and of the repurchase right arising as a result thereof on or before the
twenty-fifth (25th) Business Day prior to each Fundamental Change Repurchase
Date. To exercise such right, a holder shall deliver to the to the Trustee (or
other Paying Agent appointed by the Company) such Debentures with the form
entitled "FORM OF FUNDAMENTAL CHANGE REPURCHASE ELECTION" on the reverse thereof
duly completed, together with the Debentures, duly endorsed for transfer, at any
time from the opening of business on the date that is twenty-five (25) Business
Days prior to such Fundamental Change Repurchase Date until the close of
business on the Business Day immediately preceding the Fundamental Change
Repurchase Date, as set forth in the Indenture.

          If a Fundamental Change (except for any Fundamental Change relating
solely to paragraph (b) of the definition thereof) occurs at any time prior to
June 15, 2011, then the Fundamental Change Repurchase Price will include the
Make-Whole Premium, calculated as provided in Section 3.05 of the Indenture,
payable in cash. If the holder of any Debentures elects to surrender the
Debentures for conversion pursuant to Section 15.01 of the Indenture in
connection with such Fundamental Change, such holder will be entitled to receive
(x) at the option of the Company, shares of Common Stock, cash or a combination
thereof in respect of the Conversion Obligation, plus (y) the Make-Whole
Premium, which may be paid in cash, shares of Common Stock, or a combination
thereof.

          Subject to the terms and conditions of the Indenture, the Company
shall become obligated to repurchase, at the option of the holder, all or any
portion of the Debentures held by such holder on June 15, 2011, June 15, 2014,
June 15, 2019, June 15, 2024 and June 15, 2029, in integral multiples of $1,000
at a Company Repurchase Price of 100% of the principal amount thereof, plus any
accrued and unpaid interest (including Contingent Interest and Additional
Interest, if any), if any, on such Debentures to but excluding the Company
Repurchase Date. To exercise such right, a holder shall deliver to the Trustee
(or other Paying Agent appointed by the Company) such Debenture with the form
entitled "FORM OF COMPANY REPURCHASE ELECTION" on the reverse thereof duly
completed, together with the Debenture, duly endorsed for transfer, at any time
from the opening of business on the date that is twenty (20) Business Days prior
to such Company Repurchase Date until the close of business on the Business Day
immediately preceding the Company Repurchase Date, as set forth in the
Indenture.

          Debentureholders have the right to withdraw any Repurchase Election by
delivering to the Trustee (or other Paying Agent appointed by the Company) a
written notice of withdrawal up to the close of business on the Business Day
immediately preceding the Repurchase Date, all as provided in the Indenture.

                                      E-10
<Page>

          If cash or securities sufficient to pay the Repurchase Price or
Redemption Price with respect to all Debentures or portions thereof to be
repurchased or redeemed as of any Repurchase Date or Redemption Date are
deposited with the Trustee (or other Paying Agent appointed by the Company),
then on and after such Repurchase Date or Redemption Date, interest (including
Contingent Interest and Additional Interest, if any) will cease to accrue on
such Debentures (or portions thereof), and the holders thereof shall have no
other rights as such other than the right to receive the Repurchase Price or
Redemption Price upon surrender of such Debentures.

          Subject to the occurrence of certain events and in compliance with the
provisions of the Indenture, prior to Stated Maturity, the holder hereof has the
right, at its option, to convert each $1,000 principal amount of the Debentures
into 25.00 shares (the "CONVERSION RATE") of the Company's Common Stock (at a
Conversion Price of $40.00 per share), as such shares shall be constituted at
the date of conversion and subject to adjustment from time to time as provided
in the Indenture, upon surrender of this Debenture with the form entitled "FORM
OF CONVERSION NOTICE" on the reverse hereof duly completed, to the Company at
the office or agency of the Company maintained for that purpose in accordance
with the terms of the Indenture or, at the option of such holder, the Corporate
Trust Office, and, unless the shares issuable on conversion are to be issued in
the same name as this Debenture, duly endorsed by, or accompanied by instruments
of transfer in form satisfactory to the Company duly executed by, the holder or
by its duly authorized attorney. The Company will notify the holder thereof of
any event triggering the right to convert the Debentures in accordance with the
Indenture.

          If the Company (i) is a party to a consolidation, merger, binding
share exchange or combination, (ii) reclassifies the Common Stock or (iii) sells
or conveys its properties and assets substantially as an entirety to any Person,
the right to convert a Debenture into shares of Common Stock may be changed into
a right to convert it into securities, cash or other assets of the Company or
such other Person, in each case in accordance with the Indenture.

          No adjustment in respect of interest on any Debenture converted or
dividends on any shares issued upon conversion of such Debenture will be made
upon any conversion except as set forth in the next sentence. If this Debenture
(or portion hereof) is surrendered for conversion during the period from the
close of business on any record date for the payment of interest to the close of
business on the Business Day preceding the following Interest Payment Date and
has not been called for redemption by the Company on a Redemption Date that
occurs during such period, this Debenture (or portion hereof being converted)
must be accompanied by payment, in immediately available funds or other funds
acceptable to the Company, of an amount equal to the interest otherwise payable
on such Interest Payment Date on the principal amount being converted; PROVIDED
that no such payment shall be required (1) if the Company has specified a
Redemption Date that is after a record date and prior to the next Interest
Payment Date, (2) if the Company has specified a Repurchase Date following a
Fundamental Change that is after a Regular Record Date and on or prior to a date
that is one (1) Business Day after the corresponding Interest Payment Date or
(3) to the extent of any overdue interest (including Contingent Interest and
Additional Interest, if any), if any overdue interest exists at the time of
conversion with respect to such Debenture.

                                      E-11
<Page>

          No fractional shares will be issued upon any conversion, but an
adjustment and payment in cash will be made, as provided in the Indenture, in
respect of any fraction of a share which would otherwise be issuable upon the
surrender of any Debenture or Debentures for conversion.

          A Debenture in respect of which a holder is exercising its right to
require repurchase upon a Fundamental Change or repurchase on a Repurchase Date
may be converted only if such holder withdraws its election to exercise such
right in accordance with the terms of the Indenture.

          Any Debentures called for redemption, unless surrendered for
conversion by the holders thereof on or before the close of business on the
second Business Day preceding the Redemption Date, may be deemed to be redeemed
from the holders of such Debentures for an amount equal to the applicable
Redemption Price by one or more investment banks or other purchasers who may
agree with the Company (i) to purchase such Debentures from the holders thereof
and convert them into shares of the Company's Common Stock and (ii) to make
payment for such Debentures as aforesaid to the Trustee in trust for the
holders.

          Upon due presentment for registration of transfer of this Debenture at
the office or agency of the Company maintained for that purpose in accordance
with the terms of the Indenture, a new Debenture or Debentures of authorized
denominations for an equal aggregate principal amount will be issued to the
transferee in exchange thereof, subject to the limitations provided in the
Indenture, without charge except for any tax, assessment or other governmental
charge imposed in connection therewith.

          The Company, the Trustee, any authenticating agent, any Paying Agent,
any Conversion Agent and any Debenture Registrar may deem and treat the
registered holder hereof as the absolute owner of this Debenture (whether or not
this Debenture shall be overdue and notwithstanding any notation of ownership or
other writing hereon made by anyone other than the Company or any Debenture
Registrar) for the purpose of receiving payment hereof, or on account hereof,
for the conversion hereof and for all other purposes, and neither the Company
nor the Trustee nor any other authenticating agent nor any Paying Agent nor
other Conversion Agent nor any Debenture Registrar shall be affected by any
notice to the contrary. All payments made to or upon the order of such
registered holder shall, to the extent of the sum or sums paid, satisfy and
discharge liability for monies payable on this Debenture.

          No recourse for the payment of the principal of or interest (including
Contingent Interest and Additional Interest, if any) on this Debenture, or for
any claim based hereon or otherwise in respect hereof, and no recourse under or
upon any obligation, covenant or agreement of the Company in the Indenture or
any supplemental indenture or in this Debenture, or because of the creation of
any indebtedness represented thereby, shall be had against any incorporator,
stockholder, employee, agent, officer or director or subsidiary, as such, past,
present or future, of the Company or of any of its successors, either directly
or through the Company or any of its successors, whether by virtue of any
constitution, statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by acceptance hereof and as part
of the consideration for the issue hereof, expressly waived and released.

                                      E-12
<Page>

          If money for the payment of principal or interest (including
Contingent Interest and Additional Interest, if any) remains unclaimed for two
years, the Trustee or Paying Agent shall pay the money back to the Company at
its request unless an abandoned property law designates another Person. After
any such payment, holders entitled to the money must look only to the Company
and not to the Trustee for payment.

                                      E-13
<Page>

                                  ABBREVIATIONS

          The following abbreviations, when used in the inscription of the face
of this Debenture, shall be construed as though they were written out in full
according to applicable laws or regulations.

<Table>
<S>              <C>                             <C>
TEN COM -        as tenants in common            UNIF GIFT MIN ACT -____ Custodian ____
TEN ENT -        as tenant by the entireties                       (Cust)        (Minor)
JT TEN -         as joint tenants with right of  under Uniform Gifts to Minors Act
                 survivorship
                 and not as tenants in common    _______________________________
                                                           (State)
</Table>

          Additional abbreviations may also be used though not in the above
list.

                                      E-14
<Page>

                                     FORM OF
                                CONVERSION NOTICE

TO:  CHARLES RIVER ASSOCIATES INCORPORATED
     U.S. BANK NATIONAL ASSOCIATION

The undersigned registered owner of this Debenture hereby irrevocably exercises
the option to convert this Debenture, or the portion thereof (which is $1,000 or
a multiple thereof) below designated, into shares of Common Stock of Charles
River Associate Incorporated, in accordance with the terms of the Indenture
referred to in this Debenture, and requests and instructs the Company to issue
and deliver to the undersigned registered owner (unless a different name has
been indicated below) the shares of Common Stock issuable and deliverable upon
such conversion, together with (i) any Debentures representing any unconverted
principal amount hereof and (ii) any check in payment for interest, if any, and
fractional shares. Capitalized terms used herein but not defined herein shall
have the meanings ascribed to such terms in the Indenture. If shares of Common
Stock or any portion of the principal amount of this Debenture not converted are
to be issued in the name of a Person other than the undersigned, the undersigned
will provide the appropriate information below and pay all transfer taxes
payable with respect thereto.

Dated:
       -----------------------


                                                 -------------------

                                                 -------------------
                                                 Signature(s)

                                      E-15
<Page>

                                      Signature(s) must be guaranteed by
                                      an "ELIGIBLE GUARANTOR INSTITUTION"
                                      meeting the requirements of the
                                      Debenture Registrar, which
                                      requirements include membership or
                                      participation in the Security
                                      Transfer Agent Medallion Program
                                      ("STAMP") or such other "SIGNATURE
                                      GUARANTEE PROGRAM" as may be
                                      determined by the Debenture
                                      Registrar in addition to, or in
                                      substitution for, STAMP, all in
                                      accordance with the Securities
                                      Exchange Act of 1934, as amended.


                                      -------------------------
                                      Signature Guarantee

NOTICE: The above signatures of the holder(s) hereof must correspond with the
name as written upon the face of the Debenture in every particular without
alteration or enlargement or any change whatsoever.

          Fill in the registration of shares of Common Stock if to be issued,
and Debentures if to be delivered, other than to and in the name of the
registered holder:

-----------------------------
(Name)


-----------------------------
(Street Address)


-----------------------------
(City, State and Zip Code)


-----------------------------
Please print name and address

Principal amount to be converted
(if less than all):

$______________

Social Security or Other Taxpayer
Identification Number:


-----------------------------

                                      E-16
<Page>

                                     FORM OF
                     FUNDAMENTAL CHANGE REPURCHASE ELECTION

TO:  CHARLES RIVER ASSOCIATE INCORPORATED
     U.S. BANK NATIONAL ASSOCIATION

          The undersigned registered owner of this Debenture hereby irrevocably
acknowledges receipt of a notice from Charles River Associate Incorporated (the
"COMPANY") as to the occurrence of a Fundamental Change with respect to the
Company and requests and instructs the Company to repurchase the entire
principal amount of this Debenture, or the portion thereof (which is $1,000 or a
multiple thereof) below designated, in accordance with the terms of the
Indenture referred to in this Debenture at the price of 100% of such entire
principal amount or portion thereof, together with accrued and unpaid interest
(including Contingent Interest and Additional Interest, if any) to, but
excluding, the Fundamental Change Repurchase Date, to the registered holder
hereof unless a different name has been indicated below. Capitalized terms used
herein but not defined herein shall have the meanings ascribed to such terms in
the Indenture. This Debenture shall be repurchased by the Company as of the
Fundamental Change Repurchase Date pursuant to the terms and conditions
specified in the Indenture. If any portion of the principal amount of this
Debenture is to be issued or paid, as applicable, to a Person other than the
undersigned, the undersigned will provide the appropriate information below and
pay all transfer taxes payable with respect thereto.


Dated:
       --------------------

                                                 --------------------


                                                 --------------------
                                                 Signature(s)

                                      E-17
<Page>

NOTICE: The above signatures of the holder(s) hereof must correspond with the
name as written upon the face of the Debenture in every particular without
alteration or enlargement or any change whatever.

Debenture Certificate Number (if applicable):

Principal amount to be repurchased (if less than all):

Social Security or Other Taxpayer Identification Number:

                                      E-18
<Page>

                                     FORM OF
                           COMPANY REPURCHASE ELECTION

TO:  CHARLES RIVER ASSOCIATE INCORPORATED
     U.S. BANK NATIONAL ASSOCIATION

          The undersigned registered owner of this Debenture hereby irrevocably
acknowledges receipt of a notice from Charles River Associate Incorporated (the
"COMPANY") regarding the right of holders to elect to require the Company to
repurchase the Debentures and requests and instructs the Company to repay the
entire principal amount of this Debenture, or the portion thereof (which is
$1,000 or a multiple thereof) below designated, in accordance with the terms of
the Indenture at the price of 100% of such entire principal amount or portion
thereof, together with accrued and unpaid interest (including Contingent
Interest and Additional Interest, if any) to, but excluding, the Company
Repurchase Date, to the registered holder hereof unless a different name has
been indicated below. Capitalized terms used herein but not defined herein shall
have the meanings ascribed to such terms in the Indenture. The Debentures shall
be repurchased by the Company as of the Company Repurchase Date pursuant to the
terms and conditions specified in the Indenture. If any portion of the principal
amount of this Debenture is to be issued or paid, as applicable, to a person
other than the undersigned, the undersigned will provide the appropriate
information below and pay all transfer taxes payable with respect thereto.

Dated:
       --------------------

                                                 --------------------


                                                 --------------------
                                                 Signature(s)

                                      E-19
<Page>

NOTICE: The above signatures of the holder(s) hereof must correspond with the
name as written upon the face of the Debenture in every particular without
alteration or enlargement or any change whatever.

Debenture Certificate Number (if applicable):


----------------------------------------------------
Principal amount to be repurchased (if less than all):


----------------------------------------------------
Social Security or Other Taxpayer Identification Number:


----------------------------------------------------

                                      E-20
<Page>

                                   ASSIGNMENT

          For value received _____________________ hereby sell(s) assign(s) and
transfer(s) unto __________________________________________ (Please insert
social security or other Taxpayer Identification Number of assignee) the within
Debenture, and hereby irrevocably constitutes and appoints attorney to transfer
said Debenture on the books of the Company, with full power of substitution in
the premises.

          In connection with any transfer of the Debenture prior to the
expiration of the holding period applicable to sales thereof under Rule 144(k)
under the Securities Act (or any successor provision) (other than any transfer
pursuant to a registration statement that has been declared effective under the
Securities Act of 1933, as amended), the undersigned confirms that the Debenture
is being transferred:

     -    To Charles River Associate Incorporated or a subsidiary thereof; or

     -    To a "QUALIFIED INSTITUTIONAL BUYER" in compliance with Rule 144A
          under the Securities Act of 1933, as amended; or

     -    Pursuant to and in compliance with Rule 144 under the Securities Act
          of 1933, as amended; or

     -    Pursuant to a registration statement which has been declared effective
          under the Securities Act of 1933, as amended, and which continues to
          be effective at the time of transfer;

and unless the Debenture has been transferred to Charles River Associate
Incorporated or a subsidiary thereof, the undersigned confirms that the
Debenture is not being transferred to an "affiliate" of the Company as defined
in Rule 144 under the Securities Act of 1933, as amended.

          UNLESS ONE OF THE BOXES IS CHECKED, THE TRUSTEE WILL REFUSE TO
REGISTER ANY OF THE DEBENTURES EVIDENCED BY THIS CERTIFICATE IN THE NAME OF ANY
PERSON OTHER THAN THE REGISTERED HOLDER THEREOF.

Dated:
       --------------------

                                                 --------------------


                                                 --------------------
                                                    Signature(s)

                                      E-21
<Page>

                                      Signature(s) must be guaranteed by an
                                      "ELIGIBLE GUARANTOR INSTITUTION"
                                      meeting the requirements of the
                                      Debenture Registrar, which
                                      requirements include membership or
                                      participation in the Security Transfer
                                      Agent Medallion Program ("STAMP") or
                                      such other "SIGNATURE GUARANTEE
                                      PROGRAM" as may be determined by the
                                      Debenture Registrar in addition to, or
                                      in substitution for, STAMP, all in
                                      accordance with the Securities
                                      Exchange Act of 1934, as amended.


                                      ----------------------------
                                      Signature Guarantee

NOTICE: The above signatures of the holder(s) hereof must correspond with the
name as written upon the face of the Debenture in every particular without
alteration or enlargement or any change whatsoever.

                                      E-22
<Page>

                                                                      Schedule I

                      [TO BE ATTACHED TO GLOBAL SECURITIES]

              SCHEDULE OF INCREASES OR DECREASES IN GLOBAL SECURITY

          The initial principal amount of this Global Security is $75,000,000.
The following increases or decreases in this Global Security have been made:

<Table>
<Caption>
                Amount of decrease in     Amount of increase in     Principal amount of this    Signature of authorized
Date of         Principal Amount of this  Principal Amount of this  Global Security following   signatory of Trustee or
Exchange        Global Security           Global Security           such decrease or increase   Securities Custodian
------------------------------------------------------------------------------------------------------------------------
<S>             <C>                       <C>                       <C>                         <C>



</Table>

                                       B-1